Overheating happens for a number of reasons:
1. If it's in a confined space and turned on (small pocket, small purse, etc).
2. If wi-fi is on, it may be searching for or trying to connect to a wi-fi device.
3. If Bluetooth is on or if it's searching for a BT device or devices.
4. Charging the phone while it's on.
5. If auto-update is on in Google Play Store.
Let's check to see if it's on and if so, turn it off: Open Play Store > menu > my apps > settings > auto update (these are software updates, not updates to the information that is in the app).
NOTE: If your battery is low and your phone starts updating apps because auto-update is on, it can cause your phone to heat up.
6. Playing games or streaming videos for a long time.
7. If your Brightness is turned all the way up (Settings > Display > Brightness).
To Recap, turn off:
GPS (just as you did),
Wi-fi,
Bluetooth,
Auto-update apps.
And remember:
to charge the phone while it's off,
limit gaming or streaming time,
turn down Brightness.
Best of luck!