If all the electrical system is fine, please check that all is OK, then it seems that you have a water blockage. Check the filter is not blocked in the solenoid valve ( you are better viewing this with the shower off the wall to look inside), also the isolating valve (if fitted) is on the right way round. one last thought, check it is mains water fed as I've had so many plumbed in wrongly.
Triton Customer Care Engineer
September 2010