Download latest Android 6.0 stock firmware for X92 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: X92 Amlogic S912 4K 60FPS Android TV BOX Firmware Update 20170916
Model: X92 2GB+16GB / 3GB+16GB / 3GB+32GB TV Box
Image file size: 757 MB
Platform: Amlogic S912
Image name: q201-ota-20170916.zip
Build number: Amlogic/q201/q201:6.0.1/MHC19J/20170916:userdebug/test-keys
Inside archives: firmware + factory_update_param.aml + recovery.img
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.