I understand your situation. The problem is that unless you have the proper tools and the knowledge to use them there is not much I can help you with. You already tried the circuit breakers and any further work would have you into the electric part of the unit. I do not feel comfortable addressing that situation with you since of your own admission you know nothing about these units. Electric can kill you especially if you do not know what you are doing.
You will be better served by having a ON SITE inspection by a professional who knows what they are doing instead of you trying to play with the electric circuits.