You'd love Turbostars.
With doors released, the BILs illuminate... when the engine is running, if it has just been shut down, or if the door key is active, but the latter only if the train is above its basic emergency power level. In some circumstances, "keying on" at a door panel or on the cab desk will not immediately result in a BIL showing if the local door is open but no others.
With minimal power, the passenger door buttons generally stop working. This happens coach-by-coach, and sometimes this means you can have every-other-coach (or a random selection) with the doors released. Which is handy. (The BIL lights then start to go out, even though a release had been given, so you have no idea which coaches had a door release, which is needed for any further use of Door Deselect.)
Additionally, the driver's key is generally required to activate the part of the buzzer system which sounds when the passenger alarms are pushed. If someone has pushed the alarm on a stationary train which has been shut down, the BIL in the affected coach won't illuminate and the buzzer won't sound, and often the illuminated alarm surround also doesn't work. This means the alarm will suddenly sound via the cab buzzer when the train is started up, and if the doors are then released, you've lost all hope of seeing where the alarms have been pushed.
Yet it's worse if there's been enough power to keep the doors released, as all the BIL lamps will still be on and therefore you have no idea which coach the alarm was in. So it makes you jump then tells you nothing. Sometimes you need to further push the saloon light switch to get the alarm surrounds to light up, but if not, you have to close all doors and work out which BIL is still illuminated and therefore where the alarm is. Cue somewhere or other in the evening peak having a passcom on a stabled train which is just being brought back into use...