Not sure where the ground cables run - will look them up.

But I can't see the ground cables being the issue. A disconnected or faulty ground cable will REDUCE the current through the start assembly, not increase it.

If jumpering F105 allows the car to start then you can only conclude that the starter assembly is drawing more than 60A and therefore blowing F105. And it's shouldn't be drawing enough current to blow F105.

It HAS to be a faulty starter solenoid, despite what the shop said. Nothing else can cause your issue.

Sounds like they are trying to dodge a claim. What brand and model of starter assembly did they fit?

__________________
Wayne
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)