Motherboard fine, then stopped; no post

The Gigabyte GA-K8NF-9 powered DIY computer I built was running fine. Now, it HAS to run (because it’s my jobhunt computer), so it stops… No beep codes, but I removed and refitted the mouse/keyboard (multiple times), and then removed the CMOS battery for 10 minutes. Still nothing.

The board began to intermittantly to not post — rectified by turning on/off — now nothing. What to try next (I’m going to take the battery out for 30 minutes, now, get some more coffee and await better IT minds…)

Thanks!

Mark