Is it possible for a battery to fail overnight? It was fine when I charged it and had a run out in it through the week. Went to start it today and there's not enough juice to light the ignition bulb and it's showing 0.4v on my charger which isn't enough to start charging ffs.
You haven't left the lights on or anything like that? It's the sort of thing you do if you’re old.
If you're using an intelligent charger maybe swap it for an old fashioned one as I believe they work better on flat batteries.
Stick it on an old skool charger or run something in parallel with the battery to get your intelligent* one to charge it?
Yes, they can die overnight, the old man totally fucked my 405 battery last week. It wasn't the best when the car left me but when it came back it wouldn't even light the ignition light 5 minutes after being turned off. No doubt he left the lights on and it killed it dead.