OnePlus India — Regarding oneplus 8 pro mobile

Address:	Oneplus india
Website:	Oneplus.in

Bought one plus 8 pro mobile mainly for the IP 68 water resistant part. But water got penetrated into the mobile just at 3 feet depth with in 10 Seconds. But as per spec it shud withstand 2 mtrs water pressure atleast for 30 minutes. I immediately switched off the mobile and took it to the oneplus care but since this incident happened on Saturday which is independence day and Sunday full lock down I couldn't take it to the service center immediately but I kept the phone switched off all the time. But the oneplus technician is saying the motherboard gone because of the dealyed action and they are saying nothing will be covered under warranty and I have to pay the full amount of the phone at which I bought it to repair it. As I don't have any evidence I didn't know how to proceed further