Two days ago i bought Samsung Galaxy Note 2 N7100 (international). It had android 4.1.2 but i saw there is available update. After update to official android 4.3 my phone lost signal and started showing me "Not registered on network". 1 day passed since i am searching how to fix this thing. Tried custom rom (4.4.2) and still the same. I went back to official 4.3 for UK O2 , successfully rooted it, passed knox, installed busybox, installed ARIZA Patch. Still the same. Tried to flash MJ5 bootloader via ODIN but it shows me FAIL. And after every FAIL my phone is bricked so i am flashing all over again official ROM. I have NO backups of my EFS (in my search i saw that i need some EFS to repair this thing). I got no issue with WI-FI but only with network. If i revert back to stock android 4.1.2 will i be able to call somebody? If the answer is "YES", would somebody tell me how? I saw in some threads that with new 4.3 ROM note 2 got knox locked bootloader which is impossible to be downgraded. Please, give me guide step by step what to do to repair my phone by myself. Thank you in advance.