the problem has occurred again, but a little bit different.
1) connected to b.nuhq.nunet (at work)
2) 12:32:18.973 make a smoking break -> wifi got disconnected because of poor signal
3) back at work place: can not switch on the phone. only the hardware buttons begin to light up, but the displays stays off.
4) attached the phone to usb and adb
5) 12:43:44.938 get a logcat (logcat.txt) and dmesg (dmesg.txt)
try to get the dumpsys wifi on a adb shell as ROOT. this command hangs forever without any output. but after 30 seconds the phone vibrates and the adb logcat on the other terminal spits out many log lines (logcat-crazy.txt). after that, i can switch the display on again. but the phone was not rebooted!
after that i try to get the dumpsys as user. and this works fine (dumpsys-wifi.txt, dumpsys-connectivity.txt)
wifi is still at VERIFYING_POOR_LINK but this is wrong. the access point is 3 meter away from me
dmesg2.txt is after the screen works again. but after 10 minutes the screen is off again and i can not switch the phone on. im still connected via adb
logcat-time.txt is a is a complete log with timestamps.
traces.txt is from /data/anr/traces.txt
13:42 killed wpa_supplicant with "kill 939"
13:44 manually connect b.nuhq.nunet (failed)
13:45 switch wifi off
13:45 switch wifi on (works fine)
after that i can use the screen again.
the problem that the screen can not switched on exists for since the begin. but in the most cases it happens in connection with a poor wifi signal.