Flip the hub over. On the bottom there’s a button hidden in one of the vent holes.
Hold that button for about seven seconds, the hub’s LEDs should flash and the hub will reboot with DHCP configured so it should receive a new IP address from your router.
And then, when you have access to your hub again, put the IP reservation on your new Unifi device (Cloud Gateway, Gateway, UDR, etc.) rather than setting the fixed IP on the Hub. Much better to set that stuff on the router.