Lost all interior lights and keyless functions
 

All,
2000 Chevy Blazer "trailblazer" package 2wd 4.3 v6. I have lost all my interior vanity lighting like mirrors, glovebox, floor and overhead lighting. The keyless remote no longer works too. All my dash and all guage lighting works just fine. Took the car to a friend to reprogram the key fobs and he said i had a "BCM Error". I have not found any bad/open fuses either. I recently replaced the heater core and alternator. I have completely pulled the truck apart again looking for a connector I might have forgot to re-connect. Everything looks good. I am lost......
Any help suggestion references would be appreciated.

If the BCM is shot will the new one need to be reprogramed to accept my truck? Is that a dealership only function.