Motherboard dead or alive?

I having discussion with a ,use to be prominant Sevice Technician, from the early 80s who is now cashing on his programming skills ,that a dead or dieing motherboard can still produce a blinking cursor on the screen. You get no error messages on the monitor. I thought a dead motherboard produced no video at all. The system in quesion does not beep, but intermittently shows a blinking curser. They are going to replace the motherboard.