Proabably Question mark foldering:
Don't bet on it. There's plenty else that can fit that description.
No power supply. Those are expensive. Unless you can borrow one from someone to at least diagnose it, meh.
You could easily make the $40 asking price and then some back on parts though, and if it does boot, woot, cube!
Please don't mangle it. Get a teardown guide and the right tools, clear a bench and take your time.