R2 wont sync with board

Never had a problem with my first r2 couple days ago I purchase a used r2 (good condition ) because i had drop my previous r2 pretty hard. For some reason the r2 that i got wont sync with the board, i tried everything from switching V1 and V2, resetting the brakes amd aceleration and goes on tried every single possible and nothing.. The sync on the r2 flashes and board as well but can't find and sync not even for a little be.. I was wondering if maybe because the previously owner had a carbon gt and i have the bamboo gt makes any difference or if the is a way to reset the r2 or the board.. ?
Can't find anyone with same problem and even evolve dont know why this is happening..