[4.0.1.45] Display not turning on

REPRODUCIBILITY (% or how often): random
BUILD ID = OS VERSION (Settings > About product): 4.0.1.45
HARDWARE (Jolla1, Tablet, XA2,…): Xperia 10
UI LANGUAGE: Slovenian
REGRESSION: (compared to previous public release: Yes, No, ?): Yes

DESCRIPTION:

This was happening to me yesterday - phone display wasn’t turning on, though the phone worked fine and could receive calls (I’ve got a bluetooth headset connected). Pressing the power button shortly would show the spinner for about half a second, then the display would turn back off; resetting the phone (by holding down the power button) resulted in display turning off either while entering the unlock code the second time, or while entering the SIM card PIN (if I was quick enough to enter both, the phone then again could receive calls, but I couldn’t get the display to show anything). The issue went away on it’s own after a few hours.

PRECONDITIONS:

Unknown

STEPS TO REPRODUCE:

  1. Unknown

EXPECTED RESULT:

Pressing the power button turns the display on

ACTUAL RESULT:

About a second after pressing the power button, the loading spinner shows for about half a second, then display turns back off