Hi. I have a fault on my baxi 18He. Flashing lights indicating no water flow. I have water in my header tank in loft and I'm moving on to bleeding the system as best I can. I removed the pump and the shaft spins freely. When I turn the system back on the pump (grundfos alpha2l) lights up goes onto the setting (not sure which one it should be). Then after a few seconds the setting light goes off and only the power light stays on. Pressing the button on the front does not do anything. 3 way valve appears to be motoring fine. Can anyone point me in the right direction please?. Thanks, Liam.