Repairing Game Systems

I am starting to get a bigger and bigger stockpile of broken game systems and accessories. Does anyone have any tutorials to fix any of the following issues:

Xbox: I recieved it for free already broken. Got it just so I could keep people from repairing it and spending money on Mircosoft games. My plan is to put linux on it. Issue is that the PSU is dead so I took a ATX power supply and chopped it up to have the right pins and when I push the power button nothing happens. I decide to jumper the PSU on with a paperclip and I get the system to power up kinda. I only get an solid orange ring with no video output. Any suggestions?

Sega CD: I haven't touched this in forever to even know exactly what is wrong with it but I know that it just doesn't want to stay reading discs. I'm not sure if the laser is burned out or what but I might just start using emulators to run my Sega CD games.

Gamecube: I probably shouldn't mention this one as I have not had the time to analyze problems on it but it does nothing when hitting the power button. My friend has the same problem as me. Is the power supply or something internal a common failure in them or is it just luck that we both have dead ones? Not of any priority at all just wanting to see if it is now just decoration or of any use.