The connectors can always be replaced. The question is whether the black square component (the relay switch) is fried. If it is fried then you are probably out of luck on fixing that specific issue, because people have not been able to get replacement circuit boards since the pandemic started. Be sure and check but reports here on the forum have not been good.
You do have an amazing option though if that board is fried.
You can do a simple rewire (cut ends of the brown braided wires and the black and white smooth wires. Wire nut splice a brown with the black and other brown with the white).
The rewire would make it so that your plug feeds power directly to the heating element.
You then buy Auber PID controller.
The MES plugs into the Auber PID and the Auber plugs into the wall outlet.
You take the thermometer probe from the Auber and drop it down your vent and clip to the underside of the bottom smoker rack so it measures smoker temp.
Now you punch in the temp setting you want to smoke at and the Auber will take power from the wall and feed it to the rewired MES to hit and hold the set temp you entered.
The Auber controller should hold temp dead on or within 1-2 degrees of the set temp.
This turns your smoker into a super precise beast!!! It would be 20x better than any smoker
Masterbuilt produces even when brand new!!!
I always tell people it would be like turning a golf cart into a Ferrari. That is what you would be doing and for less money than buying a new smoker.
The only sticking point is the Auber PID controller will run you $150 before shipping and tax, BUT that is way cheaper than a new smoker AND your smoker will be better than any electric smoker you could buy until you get around $1k+ and even then it would perform just as good or better than those.
Here's the PID controller I am talking about:
Auber Instruments, Inc. Multi Purpose Controller [WS-1510ELPM] - The WS-1510ELPM is a versatile temperature controller to have in your home. It can be used for various applications such as Sous Vide cooking, controlling an electric smoker, making yogurt, dough proofing, controlling the...
www.auberins.com
They make other fancier ones with wifi and phone apps, etc. but the one I posted is the bare bones one that would do the job. Anything less expensive may not cover your heating element power needs as well.
Ask any and all questions you have about the rewire and using an Auber PID controller. I have a post that has a great amount of detail walking people through the process.
Finally, all of us rewired MES PID controller users wonder why we even debated it. The performance of the smoker once doing this simply cannot be beat!
I hope this helps :)