Hi
I've been called out to a 2016 model crown with the dual ac zapi controller in the rear.
When we turn the key, the truck makes a audible constant beep but dash display does not light up.

Ive plugged into the zapi unit and analyser shows unit powers up and no codes.
However truck is dead, just lights and horn operate.
Checked the 3 light fuses in the back next to the dual relays and battery is fine.
Can anyone share a wiring diagram or explain what usually powers up the display? Would be greatly appreciated.

Update : ive got wiring info.
Regards