Help - how to get mirror off wall?

[Octonaut4Life]

We're having our bathroom painted on Monday so have finally tried to take down the mirror on the wall from the previous owners. We thought there were caps over screws in the corners of the mirror, so that we'd pop the caps off and then unscrew the screws. However after managing to pop a cap off, it seems we've actually broken something that wasn't designed to be a cap, there isn't any obvious way to unscrew the screws and part of the mirror shattered when we tried to get underneath it. Please any advice/help on how to do this and get the mirror off safely!

The cap has snapped off in it so get a pair of pliers and get the middle bit out that is left in there, and then unscrew with a slotted screwdriver. You will see the slot for the screwdriver once you get the broken peg of the cap out

https://www.jock-of-all-trades.com/2011/09/how-to-remove-mirror-screws.html
it looks like the post of the cap has snapped off into the screw, but they are just mirror screws.

You have to unscrew the caps! A rubber glove will help with traction.

If that middle but doesn't just pull out then turn the pliers whilst holding it to unsure it. Some just pull out and some need turning

Those caps screw in, they don't pop off. Unscrew them, and then you can unscrew the screw that holds the mirror on.

Omg amazing thank you all so much! Really appreciate it.