No protection from wrong polarity.
What you can do is to check relays under the fuse box cover under the hood....since your intstrument cluster is dead too.

Yes, what they said: check the three J relays in the fuse box at the driver's window, it is almost always one or more of them has blown. These are cheap and generic and otherwise almost never fail, junkyard is the best source.

Thats probably the diode that protects the circuitry from spikes when the relay opens that blows on reverse polarity, but that should blow a main fuse upstream, failing closed circuit. Ghosting erik... Looking at the several 'reversed polarity threads' - almost all are resolved with the J relay(s) r...

Too bad you live in Toulouse, otherwise I have a whole bunch of J relays in my garage.

Next time I am in Toulouse, I can bring them for you...

À la prochaine!