Flashing the wrong firmware (including fake 5.1) will brick the device. Check the PCB (printed circuit board) between the USB ports:
is essential for backing up your existing Android 4.4 system and data before flashing new firmware. USB Burning Tool : Many 5.1 ROMs require a PC-based Amlogic USB Burning Tool for a "clean" install if SD card methods fail. The "Toothpick Method" mxq s805 firmware 5.1 download
Even among S805 devices, there are different Wi-Fi chips (Realtek 8189, 8723, Mediatek MT7601). The firmware must match your Wi-Fi module, or Wi-Fi and Bluetooth will fail. Flashing the wrong firmware (including fake 5