Question Computer auto boots when plugged in and immediately after shutdown

[Vvhiterabbit]

I recently purchased a used optiplex 9020 mini tower. As soon as I plugged it in the fans started and it booted. From there, every time I shut it down it starts back up as if it was being restarted. I went into the computer settings and made sure all the auto start stuff was disabled so I don't think it's that. The only thing I could figure out is that if I turn the computer off by holding the power button for a few seconds, the computer will turn off and stay off. I am running Ubuntu as my OS if that matters. The hard drive was pulled from my previous computer that worked just fine. Any ideas?

 

[Lutfij]

Locate the support site specific to your form factor and see if you have any BIOS updates pending. Speaking of updates, which OS are you running on that prebuilt?

 

[Vvhiterabbit]

Locate the support site specific to your form factor and see if you have any BIOS updates pending. Speaking of updates, which OS are you running on that prebuilt?

I am running ubuntu.