Cant access to the camera on iPhone 6
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.