focus whistler e mountain bike ,motor not engaging ?

[tomtom]

i recently purchased a focus whistler 3.9 electric mountain bike,bike is only a couple of months old,tested the bike yesterday before i bought it and all was working well,brought it home and had another wee shot and was okay.was ready to go my first run today and the motor is not engaging,full charge on battery,my pal who already has an e mountain bike says he can feel the motor trying to kick in for a split second then nothing,battery has been reset as well,have checked cable from battery housing to back hub and seems okay but im no expert ,any help would be great,thanks tom