I purchased a Henry GE Gas/AC Water heater. It worked for two seasons in a campervan
 
When I turn on the boiler it gives one click and the red light comes on about thirty  seconds after. We have checked the gas and everything seems to be in order
 
Any idea what could be wrong, would it be the module and if so, where can I purchase one?
 
Any ideas or suggestion would be appreciated.

 

Thanks