Aye I thought I did have a multimeter from when I was modding my Ender 3s but I couldn't find it. Anyway I survived, and you were right enough so thanks for that - new switch is in and working fine and my living room light works again as well, no breakers tripped.
I don't have a multimeter just one of those "oh **** it's live!" warning screwdrivers. An MCB panel is the little toggle switches with ON/OFF that can be tripped and reset repeatedly without needing a fuse replacement? If so I have those on the main panel for the house - I'm not fussed about the...
Quick background - a while ago I replaced most of the light switches in my flat as they were all various degrees of wonky and worn out, I encountered zero issues, all of them had what I expected to see based on tutorials I'd run through, but I avoided doing the old bedroom switch because it was...