reading this thread again it stroke me that it my problem could also be hardware related New Fairphone 2 stuck on "powered by Android" screen
while trying to install te new OS I observed abnormal behavior when it comes to charging the batterie. when plugged into a notebock, the charger symbol often just flickered between + and flash (charge icon), sometimes the battery got drained evvenmore although it was connected. I had to switch often between powersupply for chrging and the connection to the notebook for transmitting data. otherwise the phone went into energy savining rapidly or switched off.
maye the constant switch between plugin and off, notebook,charger, etc. hd caused some malefunctioning? I´ve tried different cables and was quite certain that the issue is the usb port which doesnt provid enought power, but maybe I was mistaken? what do you think?
current status: I removed the batterie over night; pluggin it in (no matter if with or without batterie only leads to the fairphone logo screen, LED is not lid at all)
totally fishing in the dark here