Hey guys, first-time posting after years of great help and tips from AC!

Anyways, I bought a used Sprint Evo 4G LTE. The ESN is clean and it is not rooted or unlocked, but Sprint cannot activate because the ESN is showing incompatible with Sprint's service. They said it was most likely flashed/unlocked for another service, and that it needs to be flashed back to Sprint in order for the ESN to be placed on my account and activated.

I know a a decent amount about rooting and ROMs with HTC's different file systems, but I don't know exactly how to reconfigure the device in order to activate it.