Hi there iphonericebath. Your iPhone 8 Plus has a water rating of IP67. Which means it can withstand about one meter for 30 minutes. Sometimes a phone can take some damage from a drop or something along that line, and then water can get inside. And also, if it wasn’t showing signs of life, did you continue trying when it could have been wet? You want to make sure the the phone is dry before you charge, or use it. Often, drying it can be as simple as a rice bath.
but I’ve also seen videos of people going in their pool to take a video. (Even with the phone underwater, the video was super clear) so unless it was defective, or took damage, I don’t know. Good luck.
and don’t let what the guy above me said hurt you. It really wasn’t your fault.
you were doing what apple, and other companies said you could. For future reference, try not to take your phone in water unless necessary. But the phone will more than likely be able to withstand some water. I try to go by, it says waterproof, but don’t wanna test it.