Several iPhone 4S users have reported that iPhone 4S gets abnormally hot. Under regular conditions, your iPhone should be cool; however, it is normal for it to get warm when charging and under heavy use. If you experience your iPhone 4S getting too hot, you may try the following suggestions:
- Reset network settings: Settings > General > Reset > Reset Network Settings.
If this does not work
- Do a hard reset by pressing and holding both the Sleep/Wake button and the Home button simultaneously for about ten seconds until you see the Apple logo.
If this still does not work
- You may try restoring your iPhone.
Further reading:
iPhone, iPad, and iPod touch (4th generation): Keeping device within acceptable operating temperatures