Depending upon the model you probably do want to open it up and sort out the clock batteries/capacitor as they are almost certain to leak and kill it, if it has not already started.Have to pick from the only two I know ... either Duke or Controller S, cuz the OG Xbox is the only one I've ever owned. And "S" it is.
I still have that OG Xbox too, pristine condition, never opened up. Go on, tell me I should mod it. Everybody does. Go on.