I'll be sure to put in the modifier that I neglected to put in the last post; I don't want to be the purveyor of potentially erroneous information.

The number one cause of failure in any printed circuit board is solder joints, especially if they're subject to physical movement. So in theory, this would be a strong candidate. Secondarily, one might look to a bad diode or something, but that's highly unlikely, and the cpu on the processor wouldn't be a candidate at all. It's very likely cracks in the solder or the wafer board itself that cause the failure. DIY repair would be difficult because of the silicone sealant that would need to be removed, and eventually re-flowed.

My indy tech has also heard that solder failure is the problem, but as he is Volvo certified, he follows protocol and swaps the board. He also reports that once swapped, the fix is effective and permanent.