Does not work

Next thing to try is to open it up if it is no longer under warranty. There could be an internal fuse, or other power conditioning electronics that have failed - possibly a failed back-up battery

See if you can open it, have a look for anything obviously burnt/unusual, take a couple of photos and post them back - we may spot something also.

If you have access to a voltmeter, check that the voltage at the socket is well above nominal 12V - should be about 11.5v to 13.2v. If it is less than 11v with the car both running and not running, then the car battery or alternator or both are probably faulty.

Try it in another car to check, ideally in a socket that works for another electronic gadget such as a mobile phone charger.

:) Next thing to try is to open it up if it is no longer under warranty. There could be an internal fuse, or other power conditioning electronics that have failed - possibly a failed back-up battery See if you can open it, have a look for anything obviously burnt/unusual, take a couple of photos and post them back - we may spot something also. If you have access to a voltmeter, check that the voltage at the socket is well above nominal 12V - should be about 11.5v to 13.2v. If it is less than 11v with the car both running and not running, then the car battery or alternator or both are probably faulty. Try it in another car to check, ideally in a socket that works for another electronic gadget such as a mobile phone charger. :)