Recently purchased a Used Dell Optiplex 390.  I know, probably a risky move but I'm struggling with money at the moment.  

Anyway, I'm trying to update the BIOS on it, only to find that the BIOS has a password on it.  I'm unable to get the BIOS password.  I read about the password reset jumpers, and there are two jumpers I can find on the board.  I think one of them is labeled CMOS something but I can't be sure.  When I switch this one to pins 2 and 3, the computer gives me a message that says "Alert, Service Mode Jumper is Set".   The BIOS password remains.  

When I switch the other jumper (I cannot find a label for it) the computer will not turn on at all.  

I feel like I'm clearly missing something simple, but what is it?

Thank you!