hi, so when you try to switch on you hear absolutely nothing, and see no lights? couple of first steps - you never know it may work: with the battery removed and the power adapter removed, press in the on/off button for about 20 seconds, then put back the power adapter and try switching on again. If no go, remove power adapter and battery again, remove and reseat ram modules. Then put back power adapter and try switching on again. Does anything happen? Did the laptop die when you were using it? Did you have any error messages in the days before this happened?
OnePlus 5T review: Hands-on