My handset is also showing TAMPERED and LOCKED. It was one of the early batches. I phoned the shop, but unfortunately as I have had the phone since early April they said they would need to send it to HTC for a warranty repair.
I brought it up in an online chat with HTC support and they don't seem to have information on this.
Update: HTC looked into it and sent me an email saying
"We have been looking into this for you. The "Tampered" words on your bootloader mean that the operating system has been modified or rooting in some way. This means that this will affect your warranty. I do apologize for the bad news regarding this."
Given that I haven't actually done anything to the OS, this isn't helpful at all. >_<
Strongly suggest you go to the shop physically and show them what it is and tell them you had not tried to root or done anything which would cause it to show tampered. So it means they sold you a bad device. And this is not obvious thing to notice so as a normal end user you should not have performed the bootloader check but the point of sell should ensure the quality of their product. Therefore, this device should be classified as DOA, defective on arrival. So the shop should exchange it.
Be strong, confused and very worried, mention this thing voids your warrenty so very serious and show a bit angry, but not too much. If it is a responsible shop or operator, it should listen to you.
The bottom line, ask them to call HTC customer rep and ask them to speak to HTC first. Emphresise you had done nothing but use the phone properly. If they can not describe the thing clearly, take the phone and speak to HTC yourself. But make sure the shop is on your side.
Worst case, if HTC still insist that you had caused the tamper, tell them to check you imei to see if you had unlocked via HTC dev website. That's the only way you would have rooted the device.
Nightmare case, they checked their record and found out your device had been unlocked, ask them to verify when that was done, they must have that info. So the date should be before when you bought it. So at this point, you are cleared and could immediately shout back: what a hell you allowed a unlocked and non-warrenty device to be on the market! And they would apollogise then you walk away with a shinny new one s.
End of story.
Sent from my HTC One S using XDA