Sometime back, an update (believe me, an OTA update) blocked all network calls on my mobile. After struggling for a while, I came to know that IMEI of my phone was set to 0. Tried many solutions (resetting the phone, clearing cache, even installing fresh OS), but none came to my rescue. Thanks to a guy (sorry for not crediting), who uploaded instructions in Russian language, and with the help of Google Translate, my phone is up and running again. Note: Before proceeding any further, keep in mind that you need IMEI of your phone (check on back panel) Download related files from here . Here is the procedure that I've followed: Install the LG driver LG Install QPST Copy the entire folder EFS Professional to C drive Unpack the archive Nexus5 the root of drive C. Using WUG Nexus toolkit: Make sure running stock Android 5.0.1 Rooted If necessary, you can reset the IMEI using backups zero IMEI from the archive. To do this, simply make a backup of your EFS in TWRP, t