Faulty Power Button on Dell Optiplex GX755 Desktop PC

[#1]

FIXED IT!!!!!!!!

The BIOS has something about the drives, where there is an item called Sata Operation. It seems to deal mainly with RAID (which I don't have so I ignored it). I compared this to the same item on my working pc. The working one has this item set to Legacy so the faulty pc has been set the same and now everything seems to be working. Hooray.

My deeply felt thanks to shutter and idonno for their support. This problem has been extremely frustrating to solve, but their help has stopped me banging my head against a wall.

[#2]

@penneck   It`s no fun stumbling about in the dark... but when someone shines a little light , you manage to find your way a bit better ... !    glad you got it fixed... seems the "legacy" was the source of the problem.

Did you manages toe get the Livie Linux Mint to boot up ? 

set your boot order to make the USB a "priority".. and then insert the usb stick, and reboot, ...

[#3]

Shutter,

I assumed that what I did yesterday (see earlier post) got the pc to boot up on the usb stick. It ran 'Windows Defender Offline'.

However, that was before I changed the boot order in the BIOS, and I didn't get anything else, so it didn't get me into Win XP. Therefore, perhaps I didn't boot up from the stick.

Is it worth me trying again, just to see what would happen, or should I leave well alone?

[#4]

Nice find! I dread to think how long it would have taken to find otherwise.

[#5]

@penneck   A tip.... when responding to someone in particular .    use "shift @ "  before  the name, and it will bring up a list of people,. if the person is not listed there, type a few letter and it will show (similar) names.. click on the one you need and it shows up..it also sends a message to the avatar of that person that there is a response

If you booted up and got a windows thing... then.... no... you did not boot from the usb stick.

You can safely put the usb stick in, before booting, and providing the usb is selected in the start up order before the internal hdd, then it should boot up into "live linux" .. and you can play around with it, to see what it can do.. .. It`s a basic desktop ( so that you can access files and folders in WIndows and save them to another usb stick ( must keep the "live" one in place though) ...

that you can carry around to any computer.. so very handy,... when you have finished, you just close down as normal... power off, remove the usb stick and when you boot again, it will be in the windows system .

You will be able to connect to the internet.... see the Menu popup  bottom left corner ... and find Firefox  ( right click and you can "add to desktop) .