NafemanNathan wrote:The mains relay is the black relay at the top of all the relays in the driver's foot well.
Normally the solders crack and loose connectivity caused by constant heating and cooling. Where has the car been stored and was this ever an issue before you parked it up?
Main relay only provides electrical feed to the fuel pump (and signal feedback loop signal to the ECU) though, nothing else.
The dash display is fed from fuses 32, 33 in the engine bay fuse box, ignition switch (IG1 position), then fuses 13 and 19 (without airbags) or 13 and 23 (with airbags) in the internal fuse box.
If all those fuses are ok and you have sufficient battery power, then either your ignition switch is faulty, or one (or more of) the various earths are faulty.
Given the car has been stood, I would be tempted to go through all the earths as the most likely cause. There are several. Probably worth starting with the ones in the engine bay. All the main ones connected from the engine to the battery and then the additional ones scattered around the bay (normally white plastic things that look like half of a multi-plug, screwed to the side of the chassis near to the headlights)
@sarah_h had similar fun with her lude a while back
If your car has an aftermarket immobiliser, then it obviously adds potential extra complication. IME they are usually the first suspect, but very rarely actually the cause... Difficult to test though, so normally the only way to be sure is to rip the whole alarm system out
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