If you have no Signal but the Sim is inside and working, then your IMEI is deleted or broken. With this Tutorial you can repair your IMEI.
You need this Tutorials read first:
How to Downgrade Newman N2 / Freelander I20...
How to Restore IMEI on Newman N2 / Freelander I20
You need this Tutorials read first:
How to Downgrade Newman N2 / Freelander I20...
How to Restore IMEI on Newman N2 / Freelander I20