Help in removing an ECU from a 1999 S80 T6
 

Found the ECU now I cant figure out how to get it out. Anyone know?

The easiest way is to have the special tool.
But it can be removed without it. But you have to remove the ECU box to make it easier.
Then there is pink/purple sliders on the bottom you have to slide a little at a time on each side of the ECU to get it loose.

But if you are thinking you can just swap a new one in that will not work.
The ECU is programmed to the car. You cannot install one from another car. The car will not run with the new one.

Sadly you need a brand new one and the Dealer needs to program it.

I knew that about a new one. But what if you bought a used ECU that has already been programmed to a identical car? I bought a used one hoping it would work.

Sorry will not work. You can try it but it has the cars Vin# programmed into it and all the cars settings.