I doubt the Thunderbolt's bootloader would be locked, HTC is usually laid back with the freedom they allow on their phones. And I think there isn't a single phone from HTC that has a locked bootloader.
Surer they may have some counters in their phones, but I think of it more as HTC trying to make hacking their decvices more interesting.
Surer they may have some counters in their phones, but I think of it more as HTC trying to make hacking their decvices more interesting.