Sounds like your heater may be groundfaulting. Can you turn your temperature down so the heater is off? If your control is digital, that may not be possible. Does your heater plug into the control box? If so, try reset the breaker once it's unplugged. If it runs--heater problem. Could be the blower, can you unplug that? If you're unsure about doing any unplugging of anything, call your local spa repair person. If you don't have one, call your local hot tub place and they may have a referral repair guy they can recommend. We do that.
"NEVER DO ANYTHING IN THE EQUIPMENT COMPARTMENT WITH POWER ON."