My Step Pre boot mode
Step1
1. Power on the unit.
2. Touch upper left of screen , result : the unit is not response. ^_^''
Step2
1. Power off the unit
2. Touch upper left of screen with plug USB cable. , result : the unit is not response. ^_^''

Step1 & Step2 don't find the usb device.

Do u have advice to me , I don't know to resolve the problem.

Please help me.