Please press with a slender object such as needle into the hole to force a shut down, when the system is not booting or has a power failure, which cannot be fixed by pressing and holding the power button for 10 seconds.
Location of the force shutdown switch (hole):
Satellite and Satellite Pro L50-A/L50D-A/L50T-A/P50-A/P50T-A/S50-A/S50D-A/S50DT-A/S50T-A
Satellite L50T-A/L50DT-A