The Motronic and fuel pump relays hang off the front of the fuse box. They're cheap and it's sensible to replace both.
If it's been sitting I've seen condensation inside the distributor cap (or an ancient rotor arm) stop an M30 from starting.
Check the connections to the Motronic speed and TDC sensor on the flywheel housing are secure, or it won't start. Check at the sensors and where they join the main wiring harness just above the inlet manifold (on a little bracket).
Could also be a dodgy car alarm.