I've just bought an used HTC One M7 that was locked to Three UK but I managed to get it unlocked via a code from ebay. The phone is on 4.1.2 and the recovery mode shows S-ON, LOCKED so I'm guessing its all stock. The CID is H3G_001 and the OTA updater keeps saying that I'm already on the latest update. The phone isn't rooted either. I've already tried resetting to factory settings but that didn't help. I've had a look at RUU's but couldn't find anything for Three UK/H3G_001.
Could anyone tell me how I could get the Sense 6 update? I've tried clearing the data/cache in the updater and google services framework but still nothing. I don't want to tamper with the bootloader etc if possible.