Ford focus central locking

It started with a temperamental key and ended with remote locking not working at all.

I took key apart (see user manual) and checked the battery - 3V no problems there.

Tried resetting remote key. That worked fine, the key made the car beep when I pressed a button. But still the locks did not respond to the key.

Then I found the turn it off and on again solution. Just unplug the Siemens box, wait an hour then plug it back in.

Look under the drivers side dashboard.
Under there attached on the right hand side right is a box which should say SIEMENS.
This is the remote control signal box.
Remove the cables attached to it and leave it for approx 1hr.
Go back to the car after an hour and put the cables back in.

Fixed!

The waiting seems important. First time I plugged it back in after five minutes and the key still didn't work.