Hi, I'm Randy. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP.
This sounds like you may have to do a factory restore.
Try this first, press and hold the Volume down and Power/Lock keys on the device for 30 seconds.
If that fails then you will have to restore>
Please reply and let me know if you need any other assistance,
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okay, connect it to the charge cable and a wall outlet charger for 15 minutes then try the procedure again while connected to the charger.
okay, that should get it back on.
When you try again, make sure and hold the volume up and home button down completely at the same time, then wait a couple seconds and press the power button. Hold all three for about 1 minute or until you see the samsung logo.
That is possible, how long has she had the phone?
okay, that is good. It will still be under warranty.
which cellular provider did she get it from?
yes, Sprint will replace it. Sprint warrants the phone to be free from defects in materials and workmanship under normal consumer usage for a period of ONE YEAR.