Powermac G4 MDD wont turn on

Okay so yesterday I picked up a Powermac G4 MDD Dual 1Ghz 2gb running 10.5.8 and all was well. When I went to change the admin account name it asked for a password, that I dont have. So after some searching on the internet I find a solution. It requires me to boot into single user mode. So I boot the computer holding Command + S (Actually a Dell keyboard, so Windows key + S. I hear the start up chime then everything shuts off. When I try to press the power button the power light only lights up as long as it's pressed. I tried reseting the pram to no avail but have no way to test the battery. I'm completely lost here. How bad did I broked it?