Disco 3 (LR3) Won't start

Right guys I went out to the D3 earlier and it wouldn't start. Wouldn't do nothing. Doors kept clunking like there were constantly unlocking and hazards flashing. Radio and sat nav screen would come on for couple of seconds then go off. And HDC message came up.

Am I right in thinking it's the dreaded instument cluster failure?

Personally would start with the battery, plus ensuring the battery terminals and leads are clean

Need to ensure with the engine off its reading around 12.6vdc , if not plse give it an overnight charge

Hope that gives u a place to start from