I brought an old monitor that I used before and tested it. When I used that monitor, the symptoms related to the s12 booting problem disappeared. After conducting several tests, I confirmed that when the s12 was connected to a monitor with a compatibility issue, the monitor did not simply not display the screen, but the main unit stopped booting. When connected to a monitor that had no issues, when I pressed the power button on the s12 that had completed booting, the device went into standby mode. However, when there was a compatibility issue with the monitor, the device did not boot. When I pressed the power button a second time, the device did not wake up from standby mode, but booted from the beginning. It seems that the s12 clearly has a compatibility issue related to booting with a specific monitor, and this issue seems to need to be resolved through a BIOS update.
