iPhone does not power up

i have an iPhone 6s Plus 64Gb and it just passed its warranty by 3 month. The phone suddenly switched off while I was using it and will not power on again. I took it to an apple authorized repair in Egypt and they told me the issue is with the main board and it cannot be repaired they also told me I am not eligible for a replacement. Is This what I expect from apple, a device that passes the warranty by three month then bricks, note the phone was never jail broken and does not have a scratch on it I always use the original charger.

please tell me what to do.