Hello,
I have a cal spa serial # 6988 model v500... It was working great... we when to use it the next evening and heat was at 85 and would not heat past 85, Turned power off for few hours reset still did not heat past 85. EC mode set to 100, ST mode set to 100, Sl mode set to 100 still did no heat past 85, I set the filter to run continuously still won't heat past 85..?
Thank You for your time and help

Easiest would be to look for voltage on terminals going to the heater. An amprobe would tell if its working.
Also if it has voltage to the element and it isn't heating, it is likely open.