Chosen Solution
My iPhone 3G displays the temperature warning. I have rebooted the phone, restored the phone, left it off for days… but as soon as I restart the phone it immediately displays the temperature warning. Could replacing the battery some how fix this? Where is it reading the temp from? where is the thermometer?
Most likely this is a faulty temperature sensor. Bring it back to the Apple store and get a fix or replacement. Good luck Frank
I have had customers that replaced their battery, and this same sort of thing shows up. Try a different battery and see if it goes away. The battery could definitely cause this. And dont be too quick to go to Apple store, they can void your warranty if they know you opened it.
