I built a 3D printer from scratch originally using a RAMPS 1.4 shield with Arduino Mega as a controller. About a week into the printer being finished and working well I installed a heated bed. It worked well at first, but after about a week one of the MOSFETs got really hot and started to smoke while the bed was heating up. After that I decided to get a new RAMPS 1.4 shield, and the same thing happened. After doing some research online, I found out that the MOSFETS on the RAMPS 1.4 typically under perform, and there are upgrades that handle the power much better. I decided to buy a RAMPS 1.6, as I had found it was rated to handle the extra current. The 1.6 worked really well for about a week, until earlier today while the bed was heating up for another print, the power connector began to smoke and caught fire very quickly. (Luckily I was aware of problems like that and watching it and was quickly able to unplug it). Note that this was a problem with the power connector and not the MOSFETs like the 1.4 board. To try and troubleshoot the problem, I plugged to power in and only the power (no USB connection) and immediately the power connection began to smoke again. So at this point I don't know how to approach this problem. I don't know what is causing it. Should I buy a new board? (I don't want to go with RAMPS again) or is there a way to fix the power connection?