95 Buick Park Avenue

Interior lights flash on and off then stay on, kills battery, had to pull fuse. Mechanics stumped. Said possible circuit board BRAIN $250.00??

I don't want to replace it on a Possible for $250.00

2nd problem, When start car then pull away, chimes go off and keep going off continiously, all doors closed properly. How do I fix this problem? Please... help....