glow worm betacom 30 not firing?

I'm a carpenter and my mate decided to stick a screw thru the 28mm return pipe, I have repaired this and refilled the system, I have bled all the rads and pressured up to 1.5 bar, fired up the system and all was ok but sounded like there was still some air in system so I turned off, re bled all radiators (no air) and now the cut out light stays on, have checked pump has no air in it and seems ok, what can I try next?