XPS 17 9700, never shuts down

I have an “XPS 17 9700” laptop. The problem is that when I try to shut it down—whether it's plugged in or not—it automatically restarts. I've updated the drivers, the BIOS, and the firmware, and I've disabled the AC power-on options. The system log shows the following:

"Power Off - ACPI power management

Power Off - WDT

Power On - Not applicable"

And it’s like this all the time. I need help with this problem.