[Q] Please help: IMEI lost on samsung galaxy note 2 GT-N7100

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http://forum.xda-developers.com – After a batter outage, it lost its IMEI. (after type, *#06#, imei is null/null). A crossed circle stands in the place of signal bar. Can not may phone call any more. The phone is rooted once. But it work perfectly after rooting until last batter outage. Is there any way to get it back? I searched the forum and no thread talk about it (QPST doesn't work for note 2). Flash new 4.1.2 firmware , won't fix the problem. Even after tried "Factory reset", the problem won't go away either. Please help with this. (HowTos)