On 13 Nov, 08:45, " wrote:
Sounds like a door interlock solenoid bolt. I think they're usually
spring loaded to return to a known state on a power-loss, and double-
ended so you can have a normally locked (bolt extended) or normally
unlocked action when unpowered.

I would have thought that having a door bolt remain in the locked
position when unpowered would contravene all sorts of H&S regulations,
as well as common sense.