LG P715 Guide De L'utilisateur page 18

Getting to know your phone
8. When the screen freezes
If the screen freezes or the phone does not respond when you try to operate it:
Remove the battery, reinsert it, then turn the phone on.
OR
Press and hold the Power/Lock key for 10 seconds to turn it off.
If it still does not work, please contact the service centre.
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