What's the display showing with the I button selected while doing this?
Does it get past s97?.
I'd expect it to show a fault code. If it doesn't detect a flow, pump running. It won't fire up but it should show a fault.
Can you hear the pump starting?
Do you get the pump symbol on the display? The nomal sequence is demand, pump symbol, then gas flame symbol.
So the boiler looks for flow, if ok it then open the gas valve by activating the fan, flame supervision to detect ignition, then after a minute turns gas up to full rate.
How long before the boiler stops? That's from initial demand to stop, and when it stops it shows S30, correct.
What stumps me is there's no fault display which is what I'd expect unles the PCB has faulted.
That was quick. Did you have a spare?
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