A couple months ago I replaced the battery in my R53 key fob and has been working flawlessly until yesterday. Just stopped working?? I tried to reprogram it but nothing. What could have happened?

 

It is possible the receiver in the inside rear view mirror has gone bad, or is corroded to the point of shorting out. They can sometimes be fixed. There are articles on the repair in the gen 1 area. Look in the stock problems area.
It is a common problem. Also there are several ways to reprogram the key and may take trying them all, to get the one that works for your car!

 

Ok I just thought it was weird that just quit working and not leading up to not working. I do have a Schwaben scan tool I wonder if there’s a option in that to program??

 

Found the problem one of my solder pins came loose. Re-soldered and wala fixed

 

I am happy to read you were able to fix it!
Congrats!

 

Thanks I was too!

 

For others who read this thread the batteries CAN be replaced. And they are cheap (less than $5) so don't feel you need to go to the dealer to get a new key regardless what they may tell you. Both mine had broken terminals but they were too short to resolder without being worried about the battery overheating. Simple fix, just search NAM and you will find how like I did.

 

Yes correct, that’s what I did three months ago. All the time is in cutting open the fob.