I've done that and its made no difference....
This looks like its fixed it.
Nokia Lumia with Windows Phone 8
Step 1
Make sure the charger is disconnected.
1. Switch the power Off.
2. Press and hold the Volume down and connect the charger, if succeed an exclamation mark (!) is shown on the screen.
(To cancel OS reset and exit to the normal mode, press the Volume Down + Power Key and hold them for 15 seconds).
Step 2
Then input Keys in the following order:
1. Volume up
2. Volume down
3. Power
4. Volume down
Step 3
The phone will reset and boot up automatically. Please note that this may take several minutes.