@Subhash

I will suggest following.
1) Flash original fw. (of product code below SIM tray)
2) Then try mix and match of main and cmt. Try not to use higher versions. North Europe seems good.
3) DO NOT try chinese or operator locked fw unless you have exhausted all other options.
4) Try to send it to country of origin and get it fixed if it is still in warranty.

Keep us posted about your progress