How is the screen of the Toshiba Z930 laptop detected as open or closed? It seems to turn off after repair when it shouldn’t

I'm repairing a Toshiba Satellite Z930-14G ultrabook, whose screen turns off when its angle is changed slightly, even while remaining open. When I connect an external monitor via HDMI as a second screen, the phenomenon occurs simultaneously on both screens. If the screen is tilted back to its original angle, both screens come back on. The behavior is not random, but systematic. I identified the problem as an erroneous detection of a closed screen state, which triggers the laptop sleep mode. The laptop enclosure was opened and closed by my customer. I didn't notice anything abnormal, even when

Question by OuzoPower on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.