[uBoat Commander]

Everything you pictured above is aftermarket crap. I hate car alarms. Think of it as a game - trace back all the wires from those & remove/splice back to original condition

Then, be sure your battery is good and fully charged. If in doubt, replace - it's the cheapest part you will ever buy for your 928. Invest in a terminal cleaner & a container of CLR, clean all battery connections, dip & clean the ground strap & the connection point to the body.

Jack up the car & block it good. Crawl under & jump the starter (alligator from large connection on solenoid to small connection on solenoid)

If you motor spins, work backwards from there. If it doesn't spin, you have a bad starter or locked engine. If you get up front & can move engine with breaker bar, the starter is bad. Do this so you don't spend a month chasing down electrical issues only to find it was your starter all along. Yes, this is from experience, as I had the quadruple crown of bad grounds, bad relays, bad starter and locked engine

(Although it sure sounds like one of those POS alarms is causing you a hassle - remove them all)

The grounds suck in these cars - My battery was 3 months old, 2 months ago I did all the cleaning of the ground strap location - And it went bad again last week, and I had to clean it again (battery acted dead no matter how much I charged - cleaned the strap location & she fired right up