Screen goes permanently black when locked

I’ve owned my Fairphone 2 for about a week now, and installed Fairphone Open on it (using the OTA package) around twelve hours ago, having no problems until about an hour ago.

Now, every time I lock the phone (or it locks itself, going to sleep while unplugged etc.) the screen remains black, with no response from the lock/power button. The phone is not frozen - if I touch the areas of the screen where the various icons should appear, I feel the force feedback, messages etc. are still received, the LED in the top left behaves as it should - but the screen is black. The only way to make the phone usable again is to reset by removing the battery or long pressing the lock/power button.

I also noticed that, for a brief period (during the last hour) the top quarter of the phone growing very warm when nothing appeared to be happening, although this is no longer the case.

Also, the phone is no longer recognised by Minimal ADB and Fastboot, although it is recognised normally by Windows 7.

I have tried dismantling the phone, to no change. All connections appeared to be fine before, and appear fine now.

Apologies if this should be posted elsewhere. I found descriptions of similar problems, but none really matching.

Any ideas? Thanks in advance!

4 posts were merged into an existing topic: Screen can not be activated by pressing the power button