Disco 2 Strange starting issue

So this morning I went to start the Disco (2003 ES Auto) as normal waited for all lights to go out and turn the key, it turned the engine over as normal but then everything died (as if the battery had been disconnected). Tried again and it was turning over but not starting and rear height warning light came on (possibly flickered a bit too), switched off the key and waited a moment, tried again and it started fine. No fault codes or anything and battery voltage is good. Temp was 1 degree so not that cold.

Sounds like a bad connection either battery terminal, starter terminal or dodgy earth

I thought this afternoon it might be a bit of oil in the loom still. I changed the injector harness in November but it’s taking a while for the oil that was in there to come through. I’ll check tomorrow

It might also be an earth though there seems to be plenty of earth-related problems on here for D2’s