I looked through the manual for your bike, got it from their website, and could find anything that said how to turn the lights on. It did say the backlight on the display comes on when you power the bike up.
Many other ebikes use a long press of the + button to turn the lights on and off. Have you asked the dealer where you bought the bike? On their website they have a form you can fill out for dealer support I would try that.
Good luck...