Josh built his own computer, but when he turns it on, sometimes it stalls on the POST (Power On Self Test). Leo says that it could be a cold solder connection, which needs to heat up a bit before the connection is made and the motherboard boots up. But that is rare these days. It could also be a flakey power supply. Another thing to check is if the RAM is properly seated.
Leo thinks the most likely cause is that the BIOS is corrupt. He should try and refresh it. If that doesn't work, he can try and reinstall the BIOS firmware. It could also be physically damaged, though.