I got the message on the dashboard that my key fob battery was low. I popped it open using the manual key and replaced with a brand new battery. Positive side up. In case it matters, in the process the five little pieces that cover the buttons (lock, unlock, trunk, remote start and panic) fell out so I had to put it back together. I had to do some work for a bit before going back to the fob so it had no battery in it for a couple of hours. I got everything back together but now the fob doesn’t work. I tried a second new battery just in case the other one was a dud. Still nothing. The red light does not come on when I press the buttons. The other fob works fine. The car starts when I put the dead fob right next to the start button. Any ideas on what the problem might be would be much appreciated.