OK, you may be onto something here - needs more checking but there is a circuit to the starter solenoid via F105.
Have a look at this..
https://www.newtis.info/tisv2/a/en/e...iliser/kP851Nc
F105 is at the top right and there's a path via the immobiliser (A146) and the start relay (K6324) to the starter assembly (M6510).
I would imagine a faulty starter solenoid would cause your fault.
AND you can easily test this by pulling the start relay (K6324) which will then isolate the starter solenoid and should not affect anything else. Car won't turn over but fuse should not blow either. If it DOES blow, then the fault has to be somewhere else - possibly in the immobiliser (A146)?
The start relay (K6324) is here...
https://www.newtis.info/tisv2/a/en/e...is-sav/UyBTGcO