My niece dropped her bike off the other day saying it won't go and could i have a look at it. Its a byocycle 20" folding bike. After checking battery and connections etc I checked the controller using a multimeter and found the Blue motor wire at fault. When turned on the display lights up with battery level full and i'm able to set the 3 assist levels but no go on the motor. I ordered a controller from ebay with the same spec as the old one but now when i turn on the battery level states low and after 10 secs all lights flash and it turns off. The controller I ordered is a" KT" type so do I need a display that is compatible ? Thanks