Harmony fresh water air lock

Hi,
for the 1st time in my ownership I've got a fresh water air lock after refilling from empty. I messed up the 1st fill by leaving the water heater drain plug out (bottom left hand corner of external vent) so drained and refilled with the drain plug back in place. the upper vent plug(top left hand corner) is closed too
The pump is running and with the cold tap open in a certain way I can hear the air but can't suck it through.

Any suggestions would be very welcome as I can't get hold hold of my habi engineer?

Thanks

Fill tank to full, open all taps. If mono mixer taps set to the middle. Then try pulsing the pump on and off. Failing that take it for a drive and repeat

Ok, thanks I'll give it a go.
Terry