Well, considering we are not psychic it is a little hard for us to advise you either. edit: I changed my mind about it being a video problem.
If it really is not BOOTING, a critical observation and not a red screen. And the screen is going red on a BIOS menu automatically coming up I would:
No beeps or error leds/lcd?
Remove all unneeded peripherals.
The fact that the red screen occasionally comes up and the BIOS is popping up on its own probably indicates a MB (possibly the BIOS flash chip) going bad.
I assume he did not try to update the BIOS before this started?
You can open it up and clean it out as well as examine the MB for flaws.
I would probably jumper the Clear CMOS header, and then remove the battery, check its voltage and then assuming it is still 3V or greater, replace it and restore the CMOS jumper to its normal (original) position. [see MB or system manual] See what happens. If battery is under 3V replace battery before re-establishing CMOS jumper to normal position.
If that fails, I would probably disconnect the HDD and first see if I could get a boot off of a Ubuntu LiveCD.
I would remove all but the stick of RAM closest to the CPU, and try again.
I would replace the stick of RAM with another stick, and try again.
Failing that I would update the BIOS to the last version available using the BIOS install boot app. if it would let me. Even if the latest BIOS version is present, I'd re-write it in case it has been scrambled.
Minimum external build.
There are other possibilities including a bad CPU (unlikely) or bad PSU, but without knowing what is in the system or how old it is it is impossible to suggest much else.
old message, in case booting is not the problem but video actually is:
But it is clearly a video problem: monitor, graphics, cable.
Swap monitor with known working. Swap cable with known working.
If video card is present and onboard video exists, pull card and try onboard. If not, then use known working card.