Q: Temperature warning & wont power off

Hello krystynamajella,

Welcome to the Apple Support Communities!

I understand that overnight, your iPhone 4 stopped charging and was showing a temperature alert when you woke the next day. There are a few different troubleshooting steps that I would recommend in this situation.

First, I would recommend reading over the attached article that explains temperature alerts.

Keeping iPhone, iPad, and iPod touch within acceptable operating temperatures - Apple Support

If the iPhone has had time to cool and does not feel warm to the touch at all, but you are still receiving the temperature alert, I would suggest moving to the next step of restoring. Restoring your iPhone back to its factory settings will help isolate the issue and rule out the software as the cause.

If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support

If after restoring the issue continues, it may be necessary to have your iPhone evaluated for service. For more information on this process, please reference the following attached link.

iPhone Repair and Service - Apple Support

Cheers,

Joe