Recently my car remote has been working intermittently. I finally got frustrated enough with it to fix it.
Step 1: Open the remote
Car remotes are pretty simple devices but there are several components that can need replacing; The case, the buttons, the battery, and the board.
To open the remote just remove the screw with a phillips head screwdriver and then use a standard screwdriver to separate the two sides of the case.
Once the remote was open I could see the problem. Part of the battery holder had come unsoldered.
Step 2: Soldering
Prepare your soldering iron. Make sure that it is in good working order and gets up to temperature. First apply heat to the two surfaces to be soldered together, then apply the solder.
I'll admit it's not very clean but it is definitely secure.
Now I just need to reassemble the remote and I'm done!