Insignia with no electrical power

[vw_99]

I was asked to help jump start a 2012 petrol insignia this morning.
Before connecting leads etc i tried the key and no dash lights came on. Connected leads and still no power to the dash.
I also tried the remote locking and interior lights but nothing worked.

The battery read 12.7v and the car has started fine before.

Checked all fuses and all are fine. It seems like power from battery is not making its way to bcm or ecu etc. I cannot see any broken wires and earths seem fine.

Any ideas where to start before taking things apart?

[Scrump]

Have you confirmed that earths are all fine by using a multimeter/test lamp or have you just done a visual on the earths?

[vw_99]

The ones i could see i uses a multimeter for.
Also done the "wiggle" test on a few wires with no change.

[vw_99]

Came home now and noticed the tail lights are on and flickering but no power anywhere else.