The manual claims you should do two things when the lights flash "check the filter" and "check the water
Assuming you have done these two, and each time you powered it off and back on the lights flash, it sounds like a technical fault.
What tempature is displayed, and does it still heat the water\maintain the tempature?
I take there is only one power supply to it, and you have tried resetting the pump\heater GFCI (trip switch)?
The fault could be a electrical one which can cost £100s to replace a circuit board, through to a fuse going which costs £1.
You need to do some troubleshooting, and see if you can get the pump to start which proves its not the pump, see if the heat element is working so you know its not the heater etc.
My guess is this is a pump or sensor issue, both can probably be fixed by a handyman it might just take some time troubleshooting it.