[Solved] OnePlus One IMEI Null, Unknown Baseband, EFS Corrupted

OnePlus One (A0001) Device No IMEI / EFS Backup Problem Fixed

So You are facing No IMEI Problem With your Device and No Network.

Then you are at Right Place to Solve this ISSUE, i've read some post on xda that flashing 
"COLOR OS" May Fix this ISSUE (Worked only for Some Users but not all).

First You Have to Flash TWRP Recovery on Your OnePlus One (Only If u Don't Have)

Unlock Bootloader (If you do not)

Download Below Files

Downloads

OPO Persist.img

After Downloaded Extract Files
Install ADB/Fast Boot
Open a Command and TYPE 

• fastboot erase persist
• fastboot flash persist persist.img

Now Reboot Your Device and Check if All are Working