The digital trail usually leads to a 2016 thread on a now-defunct hobbyist forum. The legend goes like this: a user named ElectronVolt posted a link to "Firmware 51," claiming it was a custom kernel that bypassed the S805’s thermal throttling and allowed for smooth 4K playback—something the hardware wasn't technically meant to handle.
The MXQ S805 was a staple of the budget Android TV box market, powered by the Amlogic S805 chipset. Most of these units shipped with Android 4.4 (KitKat). The jump to Android 5.1 mxq s805 firmware 51 download link
Therefore, searching for "Firmware 51" means you need the specific ROM build that contains the drivers for the RTL8189 or similar 5.1 version board. The digital trail usually leads to a 2016
: It introduced a new notification system that was more interactive and easier to navigate with a standard remote control. Enhanced Security Most of these units shipped with Android 4
Download the firmware (usually a ZIP file containing three files: factory_update_param.aml , recovery.img , and the .zip ROM). Format an SD card to . Copy the files to the root of the SD card. Unplug the power from the MXQ.