I am having a problem with a hampton bay ceiling fan remote that stopped working, changed battery and no luck, what else could be the problem?

OK.. remove the PC board from the plastic casings carefully without breaking the battery terminal contacts.. Using a hair dryer at low to medium heat... run the drier over the PC board PC board for a few minutes remembering to constantly be moving the dryer... continue until PC board is warm to the touch.. caution must be excersised not to expose plastic components to the heat... once done.. assemble and retry... alternatively as above but place under hot-air station

INTERESTING idea with the hair dryer.. . Probably voids the warranty.

Does the LED on the remote still light?

Ceiling fan remote controls - help and FAQ- Ceiling Fans N More