Download latest Android Lollipop 5.1.1 stock firmware SD card version for Acemax M8S+ TV Box from here, here or here. Download latest Android Lollipop 5.1.1 stock firmware USB version for Acemax M8S+ TV Box from here, here or here. Download previous firmware version from here.
Archive: M8S+-android5.SD CARD 20160115 / M8S+ USB 20160115 burn(android5.1)
Model: M8S Plus TV Box
Image file size: 424 MB / 397 MB
Platform: Amlogic S812
Update file name: m8s+-ota-20160115.zip / m8s+-LMY47V-20160115.img
Build number: MBX/KII/KII:5.1.1/LMY47V/20160115:userdebug/test-keys
Inside archive: firmware + u-boot.bin + recovery.img + READ ME HOW TO.pdf + factory_update_param.aml
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.