I have an action cam that uses batteries like this - the battery slides into the camera and the little terminal squares contact some springs inside the camera.
I have six of these batteries. Frequently I can't get the camera to turn on and I think it's because of poor contact at these terminals - sometimes it helps when I lick the battery first and some batteries work better than others.
I've seen some kinds of paste and gel that are supposed to be for conductivity but I'm not sure what to look for.
I've tried cleaning off the camera and the battery contacts.
Anybody got some ideas?