1.Copy hi3798mv310_force_emmc.xml and emmc_image to the USB root disk.
2.Insert the USB then power on stb, when you see the power light changes from green to red, unplug USB then reboot the stb. 
3.After recover,need delete the hi3798mv310_force_emmc.xml file in the usb,if not,when you reboot stb,will recover again.

Notice: After recovery,the box will be restored to an unsold state, the database including portal settings will be cleared.