That is a convertible tub - it can run on 110 or 220. Check to see that the jumpers are set correctly in the power block, and then check that the tiny little jumper is set correctly over on the 'mother board.'
The display is supposed to go on for a few moments and then go off until you touch a button.
I don't understand: does your power light flash and then stay ON steady or flash and then go OFF? The power light flashes when the heater gets too hot. That can be due to not enough water flow through the heater. In most cases that is from a dirty or clogged filter, or right after a spa is moved it can be due to an air bubble in the heating system. Put a garden hose down the center of the filter and blast it full flow - while you restart the 20A breaker ONLY. Then cap the filter and run the jets for ten minutes or so BEFORE you turn on the 30A breaker. That should prime both pumps and purge the heater system of air.
HTH