nomadio react powers on and off constantly

[BrianG]

Just look around for questionable looking joints.

You are getting power to the board, so the batteries, tray contacts, and wiring leading up to the board is most likely fine.

Cycling power is a common symptom in switching circuits (and is usually caused by a partial/full short somewhere), but not sure if this radio has a switching circuit.

Is there some kind of master reset button somewhere?