Used tub that I got from my parents.
Electrician wired it using existing 30A GFCI breker in main panel (parents ran tub with 30A GFCI as well)
Breaker trips once tub at temp and jets on for 30 secs or so. Trips breaker only, not GFCI.
Spoke to hot tub stores and electrical supply house.
Replaced heater element
Changed main breaker to 40A and added a 40A GFCI spa Sub Panel
Power goes in to spa control box but does not power up tub.
If I put the old 30A gfci back in the main panel, the tub works until it reaches temp.

What size circuit does the tub actually require?
What size wire did the electrician run?
Was it installed properly?
Who changed the breaker to a 40? If the wire is not appropriately sized you should not have changed it.

If I had to guess I'd say something is wired wrong.