If this is a newly wired spa, when you set the breaker, does it trip right away? If so, we must ask our electrician how he wired the neutral wire.
The neutral wire going out to the spa should not come from the neutral bar in the GFCI. This can be a common mistake some electricians may make when wiring up a hot tub.
It actually goes on Load Neutral.
Once the electrician gets it fixed there, you should have power to your spa.
Another issue could be that on initial power up, the system fuse may have blown. This 0.3 amp fuse can be replaced by sourcing a replacement fuse from any hardware store.
Then there is the issue of the actual power being out or other upstream issue that is not related to the spa. Your electrician can be sure that the correct voltage is being supplied to the spa.
On an existing installation, it is very rare for the entire power to be out and the spa to be not working at all.
Need parts for your hot tub? Get them fast from Hot Tub Outpost and have them available for your service person or electrician to install.
The Outpost even carries brand new GFCIs for 230v/50 or 60 amp systems and GFCI power cords for 120 volt plug and play spas.