Guages and warning lights

My 2000 Jeep GC has just about drove me crazier than I would normally be.
AFTER disconnecting battery for a period (seems like the longer the neg. post is disconnected, the longer it is normal), the car electric system acts normal. Then it will crash. All guages quit ( the tach quits a couple seconds after the others), chk engine light is on, key light warning is on, windows will not work, A/C will not work (fan will blow) and faint odor of hot insulation?. These are the things I know of (may be others) when it goes haywire. Also just recently noticed key can be removed at any switch position. In other words, can be driving, engine continues to run if key removed. Disconnect battery for at least an hour, then is normal.
Took it to a Auto Electric Specialist, he said could not fix it, appeared to be the BCM. He said all diagnostics pointed to the BCM. For whatever reason, he said only Jeep Dealership could fix it. I do appreciate his honesty. I am paranoid after reading online about all the electrical issues this vehicle has and the hit and miss tactics of the dealerships. Where would one take such a vehicle to have it properly diagnosed and repaired? Is there any obvious simple things I could try? I didn't know about removing the battery connection for a quick temporary fix until this website. I will gladly pay to have it FIXED, but I am not a cash cow and cannot fund incompetence. I am not trying to be rude to any duly qualified automotive diagnosticians.....old frustrated retired veterinarian