Attempt to take it apart and have a soldering gun(if not to replace a battery which if the one in it is good I would not attempt!) around; this program can at the very least give you insight on whats inside of the key fob. perhaps the plastic tab behind the button is bend or broken melt a new piece of plastic with the solder gun
We repair key fobs for main dealers and motor traders around the country and around the world. Full repair service for BMW Mini smart key as shown. Your key will be carefully taken apart and the circuit board removed.
those keys are sealed for life common repair is they cut them open on in line make repair fit new battery and you must ask for new battery they tend to last 10 years so always ask for that,, they then glue them or bond them back together cant hardly tell been done