I was givem a drone by my neighbor, no box, spare parts, not manual. Best part is, there is No branding and it looks like about 100 different generic cheap drones, so no clue what it is.
Anywho, upon taking off, EVERY TIME, the props start spinning up and just at lift off it wpuld flip over backwards. I started messing with the propellers, chamging them around, making sure the front left prop looked identical to the back right propeller (meaning left half would slant forward and the right half of the prop would slant backwards) which also made the right front prop match the back left. Next time i fired up, it lifted off beautifully. Hope this helps ya.