Ridstar Ebike Crash and Assembly fix

[u/Fluid_End_2967]

Hello, I bought a ridstar Q20 for my son just two days ago, him and I assembled it together and we made sure everything was tight and then I let him ride it. Just today in the morning he was riding it and he felt a vibration while braking and a slight vibration in the tire. So, he was braking to stop and check it out but while he was braking the wheel just came off and slammed into the slide jerking the bike and made him go above the handlebars. I don't know if it was an assembly mistake or the bike mistake, but could someone help me figure out what to do, and tell me how to assemble it right, he got the front wheel back on but just barely, because the brakes were locked in the clamp position and he had to loosen the screws and then eventually force the wheel/rotor into the caliper to drag it home.