Copy the downloaded update.zip file directly to the root directory of the USB drive (not inside any folders).
Official firmware for Mecer devices is primarily hosted on the Mustek Repository, the official distributor for Mecer in South Africa. Mustek Media Player Repository
Look for a file typically named update.zip specifically categorized under the S6 or S6+ folder.
The device will reboot to apply the changes. Once finished, you will see a success message and a prompt to delete the update file from the flash drive. It is recommended to select "No" before safely removing the drive. Mecer Xtreme S6 Hardware Specifications
Plug the USB drive into one of the S6's USB 2.0 ports. A prompt should automatically appear on your screen asking to install the update.