Hi, can you advise if the OH warning came on straight away or after some minutes\hours?
Secondly can you advise if the water was starting to warm up, and water flowing before it cut out?
The basic mechanics of hot tubs is very simple, providing the control board, heating element and pump is working other faults are not overly expensive to fix. Assuming the hot tub runs for a few minutes before cutting out and water out of the jet was starting to feel warm, its most likely just in need of a service or require a replacement thermostat.
Glad you up and running again, so I can close the case please rate the service received.