Iphone XS damaged Motherboard

I got a new XS and just when the warranty got over the motherboard gave up! I purchased the phone in California[from Apple website] but I am based in India. When I visited the Apple service centre[in India] I was told that the teams in India do not have "technical capabilities" to diagnose or fix motherboard issues but since the phone is dead [not taking charge/not responding to any troubleshooting attempts] there is a high possibility that the motherboard could be damaged.

I was also told there is no physical damage to the phone and that there is no liquid spillage. I always use the authentic cables and other accessories with the phone and now I am left wondering what went wrong. Please assist as this was a new device and I do not expect Apple quality to be so low that such expensive sophisticated devices have such low life span.