Our Hayward H300 heater did not power up when the breaker was turned on this year. After a quick look, the 3 amp fuse on the circuit board needed to be replaced. The unit power turned on, but the heater did not ignite. After a quick cleaning and checking all the connections, the unit lit and flames rolled out for a second. It was lit for about 20 seconds then shut off. Now it continues to show an IF code.