Desktop

At all times the led on the mb stays red. It stays on without the power cord plugged in. When I unplug the monitor it goes out, if any of this helps.

When it does boot, I am getting a single beep.

Power led stays on even when the computer is not running.

My guess would be that there is a crack in one of the traces or solder joints on the mb and when you push on it it makes the connection. We had in the shop about 6 months ago that was similar and ended up being a cracked trace near the kb plug. Replacing the mb is probably your best bet.

Another possibility that I have run into in the past is simply that some part of the motherboard is touchg some part of the case, or something in between them. I had a similar problem and found that there was some mobo to metal contact, so I cut a piece of anti-static bag and put it in between and solved the problem.

Sounds like there is a break in one of the circuits on the board that closes when you press down. Suspect replacing the m/b is the best long-term solution.

Good luck.
OJ

Just a comment, you may have a short under the board. The checksum error is normal, though, you said you "reset" the mother board. If you clear the CMOS you will get this message the first time it boots. Otherwise, I agree with the other answers. Cold solder loint, cracked board or debris under the board. Did the user try to install memory or a new card? Maybe he/she pushed too hard.