Download Android 7.1.2 stock firmware SD card version for MECOOL M8S Pro TV Box from here and here. Download Android 7.1.2 stock firmware PC version for MECOOL M8S Pro TV Box from here and here. Download previous version from here.
Archive: M8S PRO 20180806 / M8S PRO 20180806
Model: MECOOL M8S Pro 3GB/16GB TV Box
Image file size: 605 MB / 666 MB
Platform: Amlogic S912
Image: M8S PRO 20180806.img / M8S PRO 20180806.zip
Build number: M8S PRO-userdebug 7.1.2 NHG47L 20180806.105401.V0213 / Amlogic/q20x/q20x:7.1.2/NHG47L/20180806.105401.V0213:userdebug
Model: M8SPRO / M8S PRO
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.