Hi @max12 ,
I realize that you said that you reset the gfci but are you getting the required voltage at the control panel?
''If the voltage is OK'' have you checked that the fuse in the control panel is OK?
I don’t know the model but looking at the circuit diagram on p.51 of the [https://www.jacuzzihopperscrossing.com.au/service/owner-resources/jacuzzi-resources/jacuzzi-owners-manuals/j-200-collection-owners-manual|owner manual] shows that the spa needs 240V and that there is a fuse in the control panel
''If the fuse is OK'' then try to reset the control panel and check if that resolves it.
I found this reset procedure for a J200 series Jacuzzi so hopefully it is also applicable to your model
Press and hold both WARMER and COOLER buttons at the same time, then press the JETS 1 button once to reset the control panel.