Radio started bursting load scratching noise once in a while. Took amplifier (LEAR) out. Noticed small amount of moisture on one of the 3 wire harnesses. Carefully opened amplifier and cleaned small amount of mositure. Put back in and it played for about 30 seconds and stopped working. Purchased another one (used online). Hooked it up and it works for 30 seconds and shuts off. I've heard this means it needs to be reprogrammed. Is this true and is there a way to reprogram it without going to BMW?