I have only experienced this problem once or twice, but maybe you have an idea how to avoid my FP2 from crashing again (it went completely black, I could not switch it on again, i.e. all that helped was removing the battery).
The problem occurred while I was listening to music on Spotify with (non-bluetooth, very simple in-ear) headphones. When the first song was over, the screen turned black and the phone played dead. I have waited several minutes and tried again to switch it on before I removed the battery, but it didn't react at all.
There were some apps running in the background, most likely the Guardian app and Firefox.
Do you have any idea what might have caused the problem? I know this is only a minor issue, but I find the whole battery removing procedure a bit annoying tbh, so any suggestions are welcome.