Damaged old iPad, how to recover the information

Hello, my name is Eri. My teenage son had been using iPad mini for 7 years, taking really good care of it. He recently had a minor car accident when he was biking in the neighborhood, and a car hit and run. It was turning into a supermarket, and he was waiting to turn, one car let him turn into the parking, and the other car decided to turn at the same time and hit him. Anyway, he was okay, but his brand new pants and hoodie he got on his birthday and his beloved iPad got damaged. Of course, he's got scratched his legs and arms but the police couldn't do anything. His iPad had a hole in the screen and shuttered but he was still able to use it for 3 weeks, but finally won't be able to turn it back on anymore. We can't buy the new iPad yet, but we are hoping we can somehow transfer the information when we can buy the new iPad for him. Since I don't have the serial number, I couldn't get support help so thought to leave the comment here hoping someone would know what to do. I would appreciate any advice. Thank you.