I'm having the same shorting out issue with my MES30, they said they would warranty it for me but I had to show a picture of the serial number and cut cord.
I read the fine print and it said after we get the picture and verify your warranty we will cover it. . . I had previously told them I don't have the receipt, and asked them to if its going to be covered even though I don't have my receipt. . . Glad I didn't cut the cord just yet.
Also, I dont think its a controller issue, my unit shipped with 2 controllers and drip pans by accident and swapping them around made zero difference. Masterbuilt's response is there must be a short inside the unit.
As for fixing the connector, I'm not sure what can be done, I would say poor build quality is a factor here and I would contact them and see how you can fix it without voiding your warranty.