no power at tow bar electrics

[2cvandy]

Hi folks,
after 7 years now with a 2002 C5 2.0HDI estate I'm well used to the gremlins,,,,,,
but today she's thrown up a new one.

I plugged my trailer into the tow bar socket and had rear light one side, indicator on the other, and only one brake light.
So far so normal,,,,,, the trailer lives in a damp shed !

But, when I pulled out a rear light bulb to clean the earth contact, the + terminal sprang up and shorted to earth.

Now I have no power to any point on the tow bar socket.
The bar was on the car when I bought it, so unfortunately I have no info as to the make, or how it was wired up.
There's a beeper behind a rear panel somewhere in the back of the car, so I'm assuming it's wired through some sort of relay?
There's an inline fuse from the + side of the battery, which was blown. Obviously I thought this must be for the relay, but replacing the fuse has made no difference.
There's also a fuse in the glove box fuse board marked " Battery + " - that was also blown, and again replacement made no difference.

Any idea if there'd be a fuse hidden elsewhere?
and given that everything else was working fine with those other two fuses blown,,,,,,, what do they do?

[Homer]

There will be a box of electrical trickery in the boot somewhere. Should be just a matter of tracing back from the trailer socket to find it. That will have an inline fuse on it's power supply which will come from the wiring harness in the boot area somewhere.

[2cvandy]

Thanks for that,
as I suspected tbh.
Not overjoyed at having to pull the rear panels out of the car to find a fuse, and the replacement will definitely be routed to somewhere more accessible.