You can't renew AppleCare on a broken device.
It's really up to you to decide upon the economics of repair vs. replace. An iPhone 11PM isn't that old. If it was an iPhone 7 then I'd think differently.
For the 'iPhone Service Answer Center' click here --> https://support.apple.com/iPhone/repair/service
For instructions on how to 'Get your iPhone, iPad, or iPod touch ready for service' click here --> https://support.apple.com/HT201557
- "To protect your information and save time, follow these steps before you get service for your device."