Download Android Nougat 7.1 firmware for Acemax U2+ TV Box from 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: U2+p212_S905X_V0321_TVStock-20170730
Archive file size: 507 MB
Platform: AMLogic S905x
OS: Android Android Nougat 7.1 stock
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.