Two days ago I was browsing the internet on my Droid Razr, and it suddenly just instantly shut off. I tried to turn it back on, but to no avail. Thinking the battery had somehow died (even though I had just recently charged it), I plugged it in, and it said it had 80% battery. I turn it on, and it starts up just fine. So I figure it was just a glitch and go on with my day. Later on, the same thing happens. Now it's gotten to the point where it shuts off almost instantly. It won't turn on even if I try a hard reset (holding the power button and volume down button for ten seconds).
Before now I've never had a problem with this phone. Any idea what could be causing it?