No service / Cellular Update Failed on my iphone 7 Model A1660

Hi All,

Can someone help me with this Issue where I am facing No Service / Cellular Update Failed Issue since 3 weeks & tried all hacks mentioned by experts : https://support.apple.com/en-us/HT201415

but still it shows network for 2-3 mins & eventually shows no service.

I have even replaced my Vodafone sim card from network provider but no luck.

My Location is India (Pune)

Phone Model : Iphone7 (A1660)

Valid Purchase Date showing green status

But Telephone Technical Support & Repairs Service coverage showing Expired.

Note: I have read somewhere that this NO Service Issue is a bug from Apple Iphone 7 product & apple will repair free of cost within 4 years of make.

Any Suggestions on this Issue will be appreciated.