Phone left in car during hot day won't turn on (own fault)

A few days ago I was hanging out with my friends and I accidentally left my phone in a truck that tends to get very very hot during the day and when I went back after several hours to retreated the device is found that it wouldn't even turn on. I was hoping it was just a simple battery drain or something so when I got home I put the phone on the charger but the charging screen never popped up. I let it charge for 10 minutes and still nothing, I looked the problem up online but nothing really matched the problem cause everyone else's overheating issues were due to manufacturing issues, not silly operators making mistakes. I still followed the troubleshooting and proceeded to attempt to turn it on, take battery out and hold power button down for 1 minute to drain phone power, then letting charge for 10 minutes. After this attempt not working either I tried to enter the safe modes and other modes to see if the phone would at least activate those. Still no dice. I've come to the conclusion that it could possibly be the battery or even worse, something more internal of which there is no coming back with the phone... I really need help and I would be very thankful to get some advice on how to fix it because I can absolutely not send to manufacturer as I do not have warranty because I only use the device on WiFi because I don't have any kind of contract with it. Any help would be very appreciated. Thank you.