Fiat 500 (2012) Boot Won't Open

Hiya, I'm hoping someone can help me! I recently had my Fiat 500 MOT'd and
other than a couple of tyres it passed, and importantly everything was working
as it should.

When I picked my car up from the MOT, the instrument cluster wasn't working.
I had no fuel gauge, speedometer, rev counter - the entire dashboard was
black. The garage didn't want to know and claimed this was entirely
coincidental, but I wasn't convinced. They said because of Christmas the
earliest they could look at it is January but I need the car before then.

So I've done lots of research and armed with a set of new fuses, a pair of
tweezers, and my phone torch, I've replaced the fuse which controls the
instrument panel and huzzah - it's fixed!

Now in a bizarre twist, the tailgate won't open. It's either a huge coincidence or
something is amiss in the electrics. The button is 'clicking' but the latch isn't
being released. I've tried to find out whether a separate fuse might be
responsible for this but can't see what there is one for the tailgate. Before I try
and go via the back seats somehow (is there a way?) does anyone know if
there's anything at the front of the car or under the bonnet which might be
responsible?