Greetings!

okay...

This sounds like either a mechanical problem with the brake button causing a short, the brake lights / sensors causing a short, or a loose power wire to the empeg loosing contact with the button press. Either way, the battery icon says the empeg is seeing voltage below its threshold (10v???). Something is causing a voltage drop at the botton press.

Check your wiring for anything loose that could be causing this. Look carefully at the wiring loom for a loose power wire, any connections you made, and especially anything running near your hand brake controls.

If you don't touch the hand brake, does it fully boot and function normally?