flash my thunderbolt

[knitwit29]

I am seeing thunderbolts being sold on ebay that say they are flashed to straight talk. I have a thunderbolt I would like to use with straight talk and purchased the sims card, but they are telling me now that it is not possible. But y am I seeing them on ebay? Can anyone help me in telling me how to flash my thunderbolt to work with straight talk. Thank you