Download Android 7.1.1 stock firmware SD card version for MECOOL M8S Pro TV Box from here, here and here. Download Android 7.1.1 stock firmware PC version for MECOOL M8S Pro TV Box from here, here and here. Download Amlogic USB Burning Tool v2.0.8 from here or download Amlogic Burn_Card_Maker v2.0.2 from here.
Archive: MECOOL M8S PRO SD 20170817 / MECOOL M8S PRO PC 20170817
Model: MECOOL M8S Pro TV Box
Image file size: 861 MB / 784 MB
Platform: Amlogic S912
Image: MECOOL M8S PRO PC 20170817.img / MECOOL M8S PRO SD 20170817.zip
Build number: Amlogic/q20x/q20x:7.1.1/NMF26Q/20170817.103347.V0321:userdebug
Caution: Please do not update firmware unless you know what you are doing, you really want it or it is absolutely necessary. Firmware updates may occasionally have bad results, like bricking your device, temporarily or permanently. The firmware update process is done entirely at your own risk. Before attempting to update the firmware, back up your data.