Sure just go to sammobile.com and choose sm-t210r for the us version and smt210 for the uk and other european countries or anyother countries but as along as you are using rockettab 3.1 then it uses its firmware according to the dev (tempdroid) and no matter what stock country you flash, when you flash rockettab it changes your's tab firmware to its own firmware
So the battery drain is coming from the rockettab's firmware in your case or maybe because of the blackhawk kernel so try with the original kernel of rockettab which is the latest stock kernel then see which is better and if neither of them had no improvements then try to flash other countries' firmwarss

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Don`t be Naughty and Follow the rules
Thanks