Bad ground strap?

[hightech316]

My 08' 550i has not been cranking, only click when attempting to start.

Diagnoses lead me to believe either CAS module , Starter , ground.

Following CAS Module faults.

A0B4: CAS: Engine start, starter operation
A0C1: CAS: Output, terminal 50
A0C2: CAS: Output, terminal 50 RS

As this issue was occurring, one day car started, out of the blue. I followed ISTA + procedures and reprogrammed the CAS module . Started fine , for a week. Then back to no start, no crank.

Dash, Idrive, A/C , as well as brake lights work when key is in.

Car is in P / N as well.

Before sending CAS for repair , figure I'd doubled check the ground strap by using jumper cables from chassis to engine. It Almost turned over! I re-read the faults majority of CAS fault went away , A0B4 stayed.

I tried to jump start, slow crank no start. I am going to get the battery tested as State Of Charge is only 9% . Voltage drops 7% - 0% without being on cables .

That being said, I'm almost certain the ground strap is at-least one cause of my issues, along with battery or IBS.

Would I be able to bypass the broken ground and put a new ground coming from engine to chassis ?

Where would be Best location? At least until I get the one under the car fixed.