Cant access to the camera on iPhone 6

My friend has this iPhone 6 which is worked just fine until recently. Now she couldn't access the camera and whenever she trying to do it there is a message saying

"Flash is disabled. The iPhone needs to be cool down before you can use the flash"

She tried the "erase all content and settings" but it is useless.

Help is appreciated. Thanks.

Solution 1:

The message is self explanatory. The iPhone needs to be taken to a cool and dry place. Erase all content did worse I think. It should have been left turned off for a while in a cool and ventilated place.

Use iOS devices where the ambient temperature is between 0º and 35º C (32º to 95º F).

https://support.apple.com/en-us/HT201678

To resume use of your device as quickly as possible, turn it off, move it to a cooler environment, and allow it to cool down.

If turn off isn't an option, I would reduce all operations, airplane mode on, low power mode on, closing all apps etc.