Download Android 6.0.1 stock firmware for Qintex Q912 2GB RAM + 16/32GB ROM TV Box from here.
Video Tutorial here: How to easily update firmware on Qintex Q912 TV Box
Archive: Q912 3GB+32GB fw ota-V.20170223
Model: Qintex Q912 TV Box 3GB RAM + 32GB ROM
Image file size: 820 MB
Platform: Amlogic S912
Image: Q912-ota-V.20170223 / q9377-ota-20170223.zip
Build number: Amlogic/q9377/q9377:6.0.1/MHC19J/20170223:user/test-keys
Inside archive: firmware + factory_update_param.aml + How to upgrade the-system .xls
– repair Airplay can not be used based on IOS10.2 issue link
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.