Super73 ZX issue

I don’t got warranty anymore on my super73 zx. So here’s my problem when I turn my bike on and lift the rear of the bike, the rear wheel starts spinning faster until top speed. while giving no throttle or pedal assist. When the bike is with both wheels on the ground it does not have enough power to move. Also my display is not working and not connecting to the super app. Any tips what the problem could be?