If you want, tell me: (a) the exact firmware version you see, (b) where you downloaded the firmware file, or (c) whether the device shows any error—I’ll give targeted next steps.
If your tablet is working but you want to back it up (highly recommended), use MKTutorial Tools or SP Flash Tool (for MTK/UNISOC) to create a "Readback" backup before you touch anything.
: Some users have reported issues with specific firmware versions like BigdroidOS 2.0.0.396 failing to install correctly.