They looked off (had red lights down the side of each machine). Indeed the overhead lighting was also pretty much switched off in that area of T5 departures, it was quite dark wandering around!

Needless to say my bags didn’t make it to their (domestic) destination this morning! No idea if checking them in last night has any relevance to this, of course - not a huge issue as I was travelling home and don’t have anything urgent I can’t do without for a few days.