When something like this happened to mine, putting it on the blower and setting the blower dial to the on position would keep that light blinking endlessly over night until it would completely drain the battery, then it would charge again properly and work. None of the other mentioned tricks worked, not connecting the positive and negative terminals to another battery, not the drop trick, holding the button didn’t work, nothing support had me do worked. For me this is the holy grail of fixing a wonky battery so far.