Just had an issue with my new FP2 not charging too.
I got it yesterday, when I turned it on, the battery charge was around 30%. I plugged it in with my old Sony charger and it charged up fine.
The battery life doesn’t seem that good, so it was already half empty again, when I went to bed. So I plugged it in with my other old Samsung charger, worked fine too, was fully charged in the morning.
After playing some games this afternoon, the battery charge was getting very low again, so I plugged it in, but for some reason it wouldn’t charge. I tried both chargers, restarted the phone several times … no avail. Once I got it to start charging when it was turned off, but as soon as I turned it on, it stopped charging again.
From the heavy usage before, the phone got very hot though and I thought that might actually be the problem. So I waited like 5 minutes for it to cool down a little and now it’s charging fine again, I haven’t turned it on yet though.
Anyways, battery-life and heat-dissipation are certainly things that could be improved for FP3.