2004 Chevy Suburban Can't program new exterior mirror

Driver's side mirror (motor-driven, turn signal, puddle light, defroster) was damaged beyond repair. I successfully replaced the mirror.

Now the mirror has a mind of its own. When I unlock the car using the keyless remote, the mirror rotates all the way down. I can manually reposition the mirror. However, reprogramming the mirror position doesn't work (using the driver-specific button on the driver's side door) -- next time I unlock the car the mirror ignores the previously programmed position.

I disconnected the battery for five minutes, thinking that might reset the computer, but that didn't solve the problem.

I'd gladly reprogram all the programmable settings (seat position, light delay, lock delay, etc.) If I could get this mirror back in sync.

Any suggestions wold be appreciated. Thanks.