I will show you how to repair IMEI of Linage OS 14.1 cyanogenmod ROM for that you need to download ToolHero apk and you need to root your phone. For rooting your phone please download SuperSU package below given link
Repair IMEI of Linage OS 14.1
Downlaod HeroTool Apk to repair IMEI
Download SuperSU Zip
Download Google app (gapps nano)
Download Gapps zip and extract Gapps.zip in memory card after extracting Gapps you will find 3 file —See image
You need to install the open_gapps-arm64-7.1-nano-20170621.zip by CWN recovery or TWRP recovery.
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