Hot melt glue would probably make a good alternative to epoxy. I guess the real point here would be how much time, effort, and money are put into the cam. At some point it's going to die in a less repairable way anyhow; nothing lives forever
It does seem the second battery is on the way out. I presume you know that Gitup and Viofo are the same person? Bill runs both companies but doesn't seem to pay as much attention to this one, probably due to the much larger business of dashcams needing his attention more acutely. Historically, he moves on from older products rather quickly, so he may not have much interest in the F1 anymore. However in his favor, he sometimes will provide spare parts not normally needed or listed; he did send me a case for a cam which I had stupidly broken for a very nominal price
We're stuck with USB-based plugs and powering on cams and phones for mainly two reasons: one is that the usual voltage is what is needed, the second is that it's easy and cheap for manufacturers. Plus it's become a common usage. Better was and is available but not from a manufacturer's point of view. It's generally successful and we're stuck with it, along with any problems it has
The charging port of my phone regularly gets bits of lint and sawdust in it whereas a headphone-type socket or concentric barrel connector would be less prone to the problem. Not only does the port get clogged, the plug with it's shrouded and recessed connections gets clogged up too
Good, bad, or indifferent we get what we've got and short of re-engineering the world all we can do is work with that. Hope you can get the cam fixed without too much hassle, I really like the design of the F1 myself
Phil