Download Android Nougat 7.1 firmware for Mecool M8S Pro Plus TV Box from here, here or here. Download previous firmware from here. Download Amlogic USB Burning Tool v2.0.8 from here or download Amlogic Burn_Card_Maker v2.0.2 from here.
Archive name: M8S_PRO -NMF26Q-20170815.182813.V0321
Image: M8S_PRO -NMF26Q-20170815.182813.V0321.img
Archive file size: 798 MB
Platform: AMLogic S905x
OS: Android Android Nougat 7.1 stock
Model: Mecool M8S Pro Plus 2GB RAM + 16GB ROM TV Box
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.