No power, battery seems OK


My 2007 Mazda 2 is dead. The central locking worked once, and then when I went to turn it, it died. No, there is no power. No dashboard light, interior lights, nothing. Dead. Thinking that it's because we haven't used it in sometime (lockdown etc) I took the battery out and charged it. Only, it seemed fully charged already.

So tested with a multimeter, coming back full 12v. The fuses look OK? Looked at the cables and they all seem to go to the places they are supposed to.

Jump starting also not working, no power again, which tells me that power isn't being distributed to the car.

Problem between battery and fuse box? If so, what am I looking for?
Mazda 2 / RSTi / FJ80
I would try a different battery first and go from there or take this battery to a parts store to be tested (if you can get there). When you say full 12V do you mean 12.0V or higher? What's the age of the battery/birth date on the sticker?
Hi, thanks for the reply.

On the multimeter it was reading around 12.3, so just slightly higher. It's. Halfords battery that is 19 months old now.

Although I had cleaned the contact on the battery, I decided to also clean the negative (-) contact attached to the car. Works.

Thanks for the reply anyway. What I've learnt from this experience? Clean all your contacts first!