Asus ZE552KL Imei Repair Solution 

ZE552KL IMEI Repair

1:= For Safety First Read original Backup Firmware from Phone 

2:= Flash Eng Firmware 

Eng Rom

3:= After Flash eng firmware enable diag

4:= Read Qcn 

5:= Reset Efs

6:= Restore Qcn With Own Imei number

7:= Flash Original Firmware Backup

8:= if have phone stock so then flash ota Firmware

ota- link 

OTA Firmware

Enjoy