Spa was below temp, now it heats and won't shut off.

Is your spa overheating, heating up past 104 degrees?
If so, you have a contactor (or relay) stuck shut and the spa should go into OH at 108 degrees.
d
If your hot tub is only heating to 104 or what ever temp you have it set at and the motor runs 24 hours a day there are a couple of things you'll want to check.
First, make sure that you do not have the pump set to run 24 hours a day.
Second, you'll want to see if the pump icon is lit up on the control panel. You will want to check to see if the icon is on while the spa is supposed to be resting. During filter cycles the icon will be lit. If you are not in a filter cycle and the pump is on while the icon light is off, you have a stuck contactor (relay). The relays can be found online for less then a couple of dollars.
If you have any more questions feel free to ask.