Starter only goes click

[dadysev]

Weird issue. So i got this 3.0 e70 from the auction and noticed it would only click for a split second when i try to start it but not enough to crank the engine. So i changed the starter as its not a bad job and not expensive. While doing that i noticed someone ran a wire from the solenoid wire up to the positive jump connection on the left shock tower. I then discovered the starter was fine and who ever had it before was touching the wire to the jump terminal to get the vehicle to start. I then discovered someone ran a new ground wire from body to engine as the famous problem with the ground strap turning green and losing its connectivity happened.

After scanning the vehicle with ISTA-D it kept complaining about Terminal 50E on the CAS which sends the signal back to the DME indicating the vehicle is starting and/or running (not sure).
Took apart the CAS to find a burnt trace and diode by the starter relay in the CAS, so i repaired the trace (have a spare CAS for testing purposes) and still the same split second click.

i'm guessing the ground strap which slowly burnt away caused the vehicle to search for ground for staring and charging through other modules and wires but where???? I hope the whole can doesn't need replacing.
Has anyone else had this happen?