My guess would be the "Heater Relay Board."
If you want, you could open the front of the spa, then open the front of the "IQ-2020" and look at the smaller of the two circuit boards - specifically the one on the left to which the incoming power attaches.
If there are any signs of burning between the squarish relays, you know what the problem is.
Also, take your finger and wipe along the bottom interior of the IQ-2020 box. If there is a fine gray dust which your finger can pick up, you have confirmed the problem.
Depending upon your delivery date, this may still be under the five year warranty, assuming you are the first owner...