Back Power test button only way to turn on computer

[Melissa_69]

So here's something weird, the only way I can turn on my friend's Dell Optiplex tower computer is by keeping the back black Power test depressed and then I can power up the computer as normal. I tried to jump the switch via the motherboard and that didn't work, thinking just the power button was defective. Any thoughts?

 

[popatim]

Sound like the back power switch is defective needing you to keep pressing on it for it to stay in "ON" mode.