Download latest Android Lollipop 5.1.1 stock firmware for Acemax KII TV Box from here, here or here. Download latest Android KitKat 4.4.2 stock firmware for Acemax KII TV Box from here. To flash firmware on this box from SD card read this article.
Archive： ACEMAX KII 20160104 5.1 SW TF CARD
Image file name: KII-ota-20160104.zip
Firmware: Android Lollipop 5.1.1 stock
Image file size: 433 MB
Platform: Amlogic S812
Build number: MBX/KII/KII:5.1.1/LMY47V/20160104:userdebug/test-keys
Inside archive: firmware + factory_update_param.aml + how to reflash with TF CARD.pdf + recovery.img + u-boot.bin
How to update firmware
1.Copy all files listed below to tf card root directory: u-boot.bin, KII-ota-20160104.zip, factory_update_param.aml, recovery
2.power on the KII box and insert tf card into box.
3. go to SETTINGS-SYSTEM UPDATE–SELECT–Choose Wipe Data, Wipe Media—Update
4. Updating Progress, DON’T POWER OFF!
5. After it’s finished, the box will restart.
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.