[Iron5]

Yep, you can unlock the trunk manually with your key, consult the user manual, this comes with every McLaren also in paper form (and please don't tell us it's in the car )

 

[Iron5]

😢 It is in the car, but I am not sure whether it is the online version or not...

Shit.
I just recently read the procedure on how it would work on my 720S. It's not that easy to explain, but you should be able to take out the mechanical part of your key in your keys. Then you just have to find the mechanical lock in the front and open the trunk. But this would all be in the user manual, simply explained with pictures...

 

[Iron5]

Thank you for the quick response! I think the mechanical lock in GT is a bit different, which it locates at the left-hand door aperture...........😭

Ah ok, that can be good. I am sure you will find someone here who can help you.
Because I think the right path has given you cars4enjoying. I also strongly suspect the lack of battery voltage.