My 1998 P38 totally died last night when I switched the headlights to main beams - the engine died as did all electrics.
After research on here, I 'jiggled' (technical term) the main power connection post on the fuse box behind the battery (shown in the photo) and heard a relay click. Sure enough, I now had power and was able to start the car and move it to a place of safety..... just before the power totally died again!
As a new fuse box seems to cost over £200, has anyone managed to repair a faulty post connection like this? The visible connection at the top looks and feels sound enough, so I believe it is no longer making a good connection with the circuit board inside the fuse box......but that doesn't sound too hard to repair if there is good enough access?