No start when turning key.

Dash lights come on, but no cranking when turn the key to start.

Basics checked. Checked battery, cleaned battery terminals, checked fuses, ignition and starter relays checked.

Found the fuel gauge not working, no fuel pump or power to signal wire on starter motor.

Checked wires behind ignition barrel and found one of the wires to have power when turning the key to start.

Left the vehicle with battery disconnected, later battery reconnected and the car started.

It ran for 5 minutes or so then dash went black, the car still ran. Restarted car and the same thing; ran but no dash at all. Left for 2 hours with battery connected and wouldn't start again.

Leaning towards possible BCM issue but just stuck on what other checks to do first.