TLDR; terrible printer design, unsafe electrical design, looks better than it really is, NOT a premium Prusa i3 printer (OVERPRICED at $439), terrible quality. After 7 weeks of dealing with support and an additional $125 I finally have a functioning printer. If the printer were $200 less, it may be worth it. Your going to need to replace a lot of the components and after doing so you will be out a lot more cash. For a little more on the issues, see Design problems below. You can get really good results from the printer once tuned, but you can also get the same results from less expensive Prusa clones.I am an avid do-it-yourselfer, hobbyist, and maker of many things. I am also an engineer (a guy who's worked in the technology industry for 25+ years doing hardware, software, and much more).I received the printer and unpacked all of the components included in the kit. Also, I received an email from JG Aurora which thanked me for purchasing and informed me that all the documentation was on the SD card.I identified the SD card and inserted into my Macbook. The documentation includes multiple versions of assembly drawings in PDF, user manuals in PDF, some USB driver (for Windows), multiple packing lists in PDF and Microsoft XLSX, Cura v14.07 slicer, and finally a bunch of videos in WMV format. Since I don't have a Microsoft Windows computer, I could not open any of the WMV files. The PDF files opened without issue. The instructions were poorly translated to English but adequate for assembly. I contacted JG Aurora regarding all of the instructions in a Microsoft format and was told (sic) "You are the 1st client feedback cant open the file.Dont worry, below online videos can help !" They provided links to videos on Youtube. These were adequate to demonstrate assembly.It took about 4 hours to completely assemble the printer. After assembly, I double checked all of the connections to ensure there were no obstructions and no improper electrical connections.I plugged in the AC power and turned on the main switch. My GFCI circuit breaker immediately tripped! I re-checked all connections and confirmed everything was connected properly. I measured the resistance between Line-Neutral/Ground, about 65kOhm (no short). I tried again and the circuit breaker immediately tripped again. I sent email again to JG Aurora for support. I received a quick response from Anne asking how much voltage was measured at the power supply output. I had to explain that there was no output when the AC supply circuit breaker trips... More email exchanges and Anne asks for a photo of the power supply and serial number. I sent the photo and she responded asking me to check my local store for a 12V power supply and inform her of the price. I found the exact manufacturer and model power supply (NEWSTYLE 12V 20A Dc Universal Regulated Switching Power Supply 240W for CCTV, Radio, Security System/ LED Lighting) that JG Aurora used in the printer for $15. She told me that I should purchase that power supply and they would give me a $15 discount on their filament. I told her that I wasn't interested in a discount for their filament ($25). She then offered to send me a roll of clear PLA, which I accepted.I replaced the power supply and powered on the printer. Now the saga begins! I disassembled the original power supply and discovered a failed power transistor had burned a hole by arcing to the heatsink it was connected to, thus causing a short to ground. I informed Anne of the lack of quality control. especially for the price I paid for the printer.I performed some tuning and some initial tests and learned of the following issues:1. The temperature of the build plate (hot bed) was not working properly. When the heater was powered off, the temperature would read 80-120C. This would cause prints to stop due to over-temperature alarm, even though the bed heater was turned off and unplugged.2. The aluminum build plate was very warped, allowing for only a small 60x60mm area to be printed.3. The Z-axis lead screws vibrate on a poorly designed z-axis base placement.4. Design problems with the extruder mounting base and timing belt. Following their instructions would cause the belt to rub on itself. Had to come up with a different solution for securing the X-axis belt.I sent another email to JG Aurora, complaining again about the overall quality of the printer and the points above (as well as a few other more minor issues). I also included a lot of pictures showing the issues.I received another prompt reply from Anne thanking me for my feedback and implying that I made some mistake in assembly which would lead to so many problems. I responded insisting that I need these issues fixed and that the printer is unusable. Anne said that the mainboard would be the cause of the hot bed temperature issue. She also asked for more pictures of the entire printer. I complied and responded with even more photos. She responded and apologized for the problems with the printer and would send me a new mainboard and build plate (hot bed).After 3 weeks, I received the new parts and installed. The build plate was not warped as the original. Had only a slight droop towards the edges. There was a solder bridge across the terminal of the heated build plate. I cleaned up the solder and connected the new build plate to the printer.The replacement main board had issues as well...1. I could no longer connect to the printer on the USB port as I had been able to with the original mainboard.2. After every print, between 30 seconds to 2 minutes after the printer performed the HOME command, the circuit breaker would trip!I performed 8 test prints (~30 minutes each) and every single print would complete, but within 2 minutes after the print finishing, my GFCI breaker would trip. I swapped out the new mainboard and replaced with the original mainboard and ran 3 test prints. The circuit breaker did not trip with the original mainboard.I sent yet another email to JG Aurora with video links to the printer running and circuit breaker tripping a minute after the print was finished. Anne responded that they were on vacation and would respond in about 2 weeks.Now, 6 weeks after receiving the printer and still having serious quality issues, I get a response asking me to measure the input voltage and output voltage of the power supply and check all my connections. Also to ensure the power supply is not touching the metal frame.I responded with the information requested and indicated a safety issue with the printer design. I was told to check that Line and Neutral were not reversed. Also, try an "isolated power supply" and that the "trip problem is expected to have little to do with the printer itself". See Design problems below for details on electrical safety.I again described how the problem (tripping GFCI breaker) follows the mainboard in my testing. I again pointed out the electrical safety issue.Anne responded with the following:"We can send you a mainboard and new power supply to finish this case.But pls note that the problem you met is cause by power supply 90% !Thank you for your advice but we are professional 3d printer manufacturer and we know our machines !" I did respond stating that I would be very happy if the new components would "finish this case". Also mentioned that "professional" 3D printer manufacturers do not have this many problems with their printers.While I was tired of waiting for a functional printer, I ended up purchasing a different mainboard altogether, OSOYOO MKS Base V1.5 (OSOYOO MKS Base V1.5 3D Printer Controller remix Board ( Combination of Arduino MEGA2560 + RAMPS1.4 + 5PCS A4982 drivers) With USB Cable). The printer is now working again, but I'm out another $40.After 3 weeks and I received another replacement mainboard and power supply.A week later I also had to purchase another power supply, as the first replacement supply died. These power supplies (NEWSTYLE 12V 20A Dc Universal Regulated Switching Power Supply 240W) do not hold up well. I believe that the rating of the power supply is overstated. I purchased "EPBOWPT 12V 30A Universal Regulated Switching Power Supply" (EPBOWPT 12V 30A Universal Regulated Switching Power Supply Driver for LED Strip Light CCTV Radio Computer Project) for $20. This supply is slighter larger in size, which required drilling new mounting holes on the printer, but it fits. No problems since.I spent a total of $75 to get my printer working. This is far from acceptable for a $439 Prusa 3D printer. I expected top quality for the premium price (compared to other DIY Prusas). Total price $514 and 7 weeks before I had a functioning printer.Design problems:The metal frame may seem like it would add structure and make for a more solid printer, but that is NOT what really happens with this printer frame. The way the horizontal bed assembly is attached to the metal frame leads to a lot of movement of the frame. Especially if you ever need to touch the control knob during a print. The metal frame will move in relation to the print bed causing the print nozzle to move up and down during printing. Also, any change in tension of the filament will do the same thing, leading to gaps or bulges in the print layer.The front of the Y-axis (print bed) assembly rests about 2mm lower than the rear of the assembly. This attributes to leveling issues with the print bed.The Z-axis Acme lead screws are allowed to float while the axis is guided by 8mm rods attached to the metal frame. This is not a bad design except for the mounting base is made from aluminum and the mounting hole is slightly off causing one of the lead screw to rub on the metal. I was able to make some bushings to quiet the chatter caused by the lead screw contacting the block.Electrical SAFETY issue. This printer uses a metal frame. The DC power supply is connected to earth ground via the 3-prong C13 plug. This provides a ground to the chassis of the power supply, however, the power supply chassis is FLOATING, electrically isolated from the printer frame. If the Line wire were to come lose and touch the printer frame, this would NOT trip the circuit breaker, but instead expose a person to 110/220VAC! This is a serious design flaw. I added a ground wire from the C13 connector to a point on the frame.I also purchased 0.19" aluminum plate ($50) and secured the metal frame and raised and secured the front of the Y-axis assembly. This has significantly helped with the larger prints, allowing me to utilize nearly the entire 200x200mm of the print bed. Whereas before, I was restricted to about a 80x80mm area without running into problems printing.I cannot recommend purchasing this printer (or anything else from JG Aurora). I wish that I could have returned this but because of the many delays dealing with support, I am well past the 30-days A-Z guarantee from Amazon. The support seemed friendly at first, but quickly proved they either did not understand the problems or were condescending and arrogant (asking for pictures of a tripped circuit breaker, warped print bed, voltage measurements from non-working power supply, asking to verify no shorts to ground after sending video of a print in progress, etc).