Broken wire in the elephant trunk--the loom from body to trunk.
The break won't be visible, so yank the wires apart. Power is all color coded. See Bentley or spaghettidecoder if you want to see wiring diagrams, but you'll need to yank on all the grounds anyway. You need the trunk 'open' switch...I believe that's part of the trunk latch mechanism, but I'm not positive.
In any case, yank each wire from the top and bottom. If it breaks, it will be one of the ones you need to fix. I suspect you'll have more than one going...so yank them all. When this starts to become a problem in a year or two, you can rebuild the whole thing for $20 or so (more if you get really good wire). I went two years after my first issue. Was in that loom about 5 times in that 2 years, until I gave up on the whole thing...and at dealer, it's a $600 harness!
Inline splice, solder, shrink tube.
Search me and 'elephant trunk' ...search youtube for 'how to solder wires'
Oh, cut ziptie off from bottom of the elephant trunk (inside the trunk) and push the hose down into the trunk to expose the wires. Leave the final grommet just in the hole so you can get it out.
