Dell Pro Plus Tower(QBT1250 ) is automatically boot when the power cable is connected to the wall outlet

Is the QBT1250’s motherboard or power supply faulty?

I recently buying a QBT1250 Tower – Windows 11 Pro, Core Ultra7 265, 360W Power Supply, No additional graphics card.

It is automatically boot when the power cable is connected to the wall outlet.

Steps to reproduce
1. Reconnect the power cable from the wall outlet.
2. The power button light turns on, and the QBT1250 powers on automatically (white light remains on).
3. After about 10–15 seconds, the power turns off automatically. and power button light is turned off.
4. Pressing the power button again and it is boot the QBT1250 normally and it operates without issues.
5. Shut down the Windows 11 using the windows shutdown menu.
6. The power button light is turns off.
7. Leave the power cable connected to the wall outlet without disconnecting it (for 1 hour or even over 24 hours).
8. Pressing the power button the boots of the QBT1250 is normally and it operates without issues.
9. Shut down the Windows 11 using the windows shutdown menu. (no sleep menu). power button is thrned off.
10. If step 1 is repeated, the same behavior occurs: the system powers on automatically and then shuts down.

- The BIOS “Power Loss Recovery” option is set to “Power Off.”