The early 129's had an over voltage protection fuse and relay. It was intended to protect the electronics from voltage spikes like those which can occur when jump starting. The fuse blows and causes the symptoms you describe. I don't know if that was carried through to the later models like yours. If you have one, in the old 129's, it is located under the hood on the passenger side at the rear ( near fire wall ) under a plastic cover held down by 4 or 5 large philips head screws. In my 1991, it is a blade type fuse on top of a plug in relay.

__________________
Resistance is Futile.