Water Heater problem

Make sure you have turned the gas on AT the heater...there should be an isolating valve close to the heater...maybe in a cupboard base nearby. Failing that, the control module might be malfunctioning...but at that stage you'd probably be wise to engage a gas fitter...gas is dangerous stuff !

yours is a storage tank type & sounds like a power problem, & could be as simple as a bad connection, very few vans a wired with tinned wireing & marine connectors so clean all the connectors & you can even spray them with connector cleaner but when vans are left for a while they grow some good crust on items & it could be that it has an air lock open all tapes & O/p valve as it may be that it thinks there's no water to heat make sure there’s water flow
on instance types it’s the flow switch (on the water) that tells the gas to ignite that often gets stuck & often needs a tap or even to just hold the hot water relief valve open gets them going.
good luck but remember its gas & it will blow you up if your not carefull

Thanks for your comments. Appreciate your time