Boot your tablet back into Fastboot mode ( adb reboot bootloader ). Wipe the current system by typing: fastboot erase system

If you want, I can:

You need a custom recovery designed for the SC9863A to flash new ROMs. Download a matching TWRP image for Go to product viewer dialog for this item. Boot to fastboot mode. Flash: fastboot flash recovery twrp.img . Reboot directly into recovery. Step 3: Flash the Custom ROM

On your tablet, go to Settings > About Tablet and tap Build Number 7 times.

Because the device relies on a Unisoc chipset rather than mainstream Qualcomm or MediaTek processors, standalone device-specific custom recovery modules like TWRP are not widely maintained across independent repositories.

Choose bgZ (includes Google Play Services) or vanilla (no Google apps, requires manual flashing of MicroG or GApps).