We are dealing with a DEAD PC (google that.)

You don't need the HDD for this round. And you don't need RAM in fact. Or display. I go for beeps and status LEDs.

A lot of Dell's just sit in reset when the BIOS battery is too low or gone. You have a DVM to check that or just replace it. You also get out the DELL DOCS on your model to see if it has jumpers. Sometimes when the password reset or other jumper is in the wrong place, it hangs.

Finally there's a reason it was free. It may be dead.