I have an 2001 Clio. The key will not open the central locking ?

locking but i can open the doors manually & start the car without a problem.
I thought the battery must have gone as the red led was not lighting up. I opened the key fob and found that a small piece (square) had broked away from the soldered joints.

I've been told this is the micro switch!?

Can anyone shed any light & advise if all i need to do is get the broken piece re-soldered?