Take a USB flash drive with a capacity of at least 8 Gb and format it in the exFAT or NTFS file system (FAT32 is not suitable).
Download the firmware file from the link above and write it to the root of the flash drive as one file (no need to unpack).

Insert the flash drive into the USB slot

On the tablet, press the Running memory (1) inscription repeatedly until the Local update (2) button appears.
Press Local update.

Wait for the firmware to load

Wait for the firmware to update, it will take about 18 minutes and can stay at 22-24% for a long time