I have an A101IT-V6 running 2.4.82. When I select Update Firmware from the boot menu I get the message "USB connection: Press OK to disconnect".
When I press OK, I get "Update failed: (1)" and it takes me back to the main boot menu.
I had this exact issue and I found that my file was renamed in download it added(1) to the file name as I saved in the same directory as the firmware (same name) make sure it has the exact file name and try again, thats what worked for me after I removed the incorrectly named file from the tablet