If you have a Suburban water heater the reset buttons are covered by the rubber cover just under the pressure relief valve. The right is the gas and the left is the electric reset buttons. Also if the water inside the water heater is not below the preset limits the gas side will not come on. If you turn the switch on for the gas inside the MH and the red light does not come on then the water is too hot for it to ignite. If you run the hot water for a few minutes then try to turn it on. Sorry I don't have the diagram for the WH.
Linear Mode
