My son’s LG K10 phone has been flashing on the lock screen; the lock screen will show and then turn black like a strobe. We are unable to use the touch screen at all. I’ve tried holding the power and volume down buttons at the same time and it is not working. As far as we know, he hasn’t spilled anything on it, nor has he dropped it. This phone is completely useless right now, 0% access to anything. Please help!