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 as long as the tablet has a good charge or is plugged in during the reset.
You need an micro sd card and an original firmware. Put the original firmware on the root of micro sd card(you will have a folder dload withe the firmware inside), now with your tablet off put the micro sd card on the tablet an then press power. Update will start automatically.