Because this hardware is older, finding a working "firmware 51" (Android 5.1) often involves using custom ROMs originally developed for similar devices, such as the K1 or MXQ Pro. Where to Download MXQ S805 Android 5.1 Firmware
Updating your TV box to Android 5.1 Lollipop can significantly improve its functionality, allowing it to run newer apps that require a higher API level than the original Android 4.4 KitKat. mxq s805 firmware 51 download link
Unzip your downloaded firmware files. You should typically see files like factory_update_param.aml , recovery.img , and a .zip or .img firmware file. Enter Recovery Mode: Insert the SD card/USB into the box. Unplug the power. Because this hardware is older, finding a working