Screen picture frozen and unresponsive to all touch and buttons.

Whilst browsing on eBay, I left the tablet for several minutes. The screen normally goes into sleep mode but didn't this time.

The screen remained on and frozen. Totally insensitive to touch and unresponsive to the on/off button and to the volume control button.

The Acer logo screen briefly appeared after a few minutes but then the screen went blank and has remained so ever since yesterday.

I have tried to do a factory reset but without result.

The procedure of button pressing involving the on/off and the volume buttons had also failed to have any effect.

The battery was charged before this screen blackout and the tablet has not been dropped or knocked in any way.

Does anyone know of way of solving this problem without involving Acer Support?

Thanks. TJD in England.