Gives up balancing, leaving the robot waiting to be stood back up.
Issued by BB.NSK.Balance.Controller when the lean goes past the angle it
can recover from. The controller brakes the wheels itself; this only moves the
state machine, so that the panel and the NeoPixels — which paint from
[:state_machine] transitions — tell the operator it is safe to pick up.
It is not a safety transition. The robot stays armed, because it is expected to be stood up and carry on, and disarming would mean a fresh arm and its prearm checks each time it tipped over.