Fastrack — fastrack reflex 2.0 not working

I purchased a fastrack reflex 2.0 4 months back. Its tap button has stopped working. How can i get it replaced. My order id from fastrack official website-876836 dated back to 31/7/19. The model was working fine. But automatically it went in sleep mode after which i could use the tap button. Though it is in sync with the mobile app. Do probe in the matter asap