Mine always does weird stuff when it is wet. Sometimes works sometimes doesn't. As soon as it dries out it works with no problem.

By not knowing your model # its hard to say but start with the exhaust sensor clean it check connections reinstall. Its not the firing thats an issue how it sounds. I wish I could show you right where its at. Please check with manufacturer easy fix. Let me know.

You likely have either a bad control board or a bad membrane switch.

I just went to Amazon or A1 Pool and ordered the sensors.

After 7 years with my Sta-Brite Max-E-Therm, I knew one would act up. Being a car mechanic for years, instead of replacing or cleaning one sensor on coolant or heat, you should do all and then never have to do again for 7-10 years! Also mine had a thermostat I changed as well because I run a chlorinator and have had scale a few times; I wasn't going to chance that either. Whole cost was around 185.00 and a Saturday afternoon because of location of my heater is tight.

I think there is a problem with your membrane switch that is the reason it is not working properly.