Completely Dead iPhone 8 (No life signs)

Hi. I was charging my iPhone and when I picked it up 5 mins later, it was completely dead. It didn't turn on, it didn't sync with anything or even be recognized by any other devices I have, I've tried all of the solutions online, (disconnecting the earpiece speaker and battery, using wireless charging, holding down buttons, trying fast chargers) everything and nothing helped, theres not any data I need off of it but I do want to sell it. Can anyone help?