turn tablet off then KEEP HOLD OF VOL + AT THE SAME TIME KEEP PRESSING THE POWER BUTTON UNTIL DRIVER INSTALL ON PC OR LAPTOP THEN FLASH PROCESS WILL BEGIN WILL TAKE ABOUT 3 MINS TO FINISH THEN TABLET WILL REBBOT AND BE WORKIN AGAIN NEED ANY HELP JUST ASK
Also, either remove the battery,... or just let the battery die. I had a tablet do that when i had a failed usb connect. Couldn't get recovery mode or anything. Let the battery die while powered on. In the morning, if it is dark, plug it in and power it on.
If there are no instructions there specifically for your tablet, try some of the methods for other tablets. One of them will probably work and you won't hurt anything by trying.