This has worked (so far!). I couldn't unsolder the metal box as it needed lots of points heating and releasing at once. I tried cutting off those parts of the solder standing proud, but it still wouldn't budge. I used wire cutters to nip off the box on three sides, then lifted and cleaned...

Gottit! Magic - thanks very much! :)

:lol: Thanks!!! Yes, I found your advice (lots of it), but the bits about MHz threw me. No numbers on the box label, or circuit or any component, gives any clues about this. The only number which might be (on the label of the box of mine) says “251.8”…? So, it’s safe to assume that...

My key fobs both stopped working a couple of weeks ago. Looked online here, there and everywhere. Bought new fob batteries: no difference. Found 4-digit code and performed 5-minute key ceremony. Door opened. Opened bonnet. Removed car battery earth. Removed headlining (I have no sunroofs but...