System Halted! Must Power down.

Hi, I recently found an old dell desktop and its a Windows Vista Buissness OEMAct and it won’t let me put in the system password at all, i thought it was the keyboard or something but i tried it with another one and it wont let me type anything for the password! And now it just says System Halted! Must power down and it won’t even let me do that either. I was wondering what I should do to fix this?