Galaxy 2000 lx power shower cuts out

[Reluctant plumbers]

Hi
After not using the shower for a few weeks, when turning on it glugged and a little water came out of the hose. I turned the flow up to maximum, the water flowed fast for all of 2 seconds, then cut out. That is all it will do now, I turn it on, fast water flows for 2 seconds then it stops. I can push the on button many times and it will always flow for 2 seconds. I cannot adjust the flow, not sure if this is because of the limited time it flows for or because it is 'locked' onto the fastest flow somehow. I tried changing the solenoid and this didn't work, exactly the same problem. It doesn't matter how long it is left for, it will not flow for more than 2 seconds.
This has had a new pcb in the past, does this sound as if it has gone wrong again or is there something else I can check?
Thanks

 

[seco services]

When it cuts out check with a multi meter to see if solenoid is still getting power if not then more likely a pcb fault.
i take it you have checked to make sure the main shower is still getting 230v etc and all connections are tight.

 

[Reluctant plumbers]

To Seco Services
Thanks for your answer. Here is an update on shower in case it is of help to you.
As shower had only been using a small amount of water we didn't bother to put the boiler on and today had usual 2 second at a time shower. It stayed on a fraction longer than it had been, long enough to get the flow back down to number 1 and it stayed working as normal. Not sure if being on number 7 flow had been too much for the thermal cut out with the hot water pumping through at full strength and having cooler water today allowed it to stay on long enough to reduce the flow.
Whatever the reason, we are just happy to have it working.