Mysterious ticking noise in boot

[ZyzzS3]

Hey guys,
I have a mysterious ticking noise coming from the boot of my 2007 S3 (no it’s not a pipe bomb for those YouTube fans).
Its coming from the rear RHS (when looking into the boot from the back) above the rear wheel. Where the Bose Amplifier is.
It’s only when the car is off, locked or unlocked and is spaced about 15-20seconds apart. It sounds like a switch being clicked on....
I have no idea where to start, any suggestions would be greatly appreciated as it’s draining the battery significantly.
Thanks in advance!

 

[ZyzzS3]

I have an aftermarket head unit in there, could it be causing the Amp to continuously turn off/on?

 

[NHN]

Remove head unit & together/seperately remove amp fuse, retest.

Only few things sit in that area, parking, convenience, towing modules of which S3 doesn't have towing & the fuel flap solenoid & parking module buzzer.

Start with amp & head unit, report back.