Download latest Android KitKat 4.4.2 stock firmware for CS918S 1GB RAM / 8GB ROM TV Box from here or from here. Download latest Android KitKat 4.4.2 stock firmware for CS918S 2GB RAM / 16GB ROM TV Box from here or from here. Download a newer firmware from here.
Archive： CS918S Allwinner A31 Android Mini TV Box 1G 8G Firmware 171576 / CS918S Allwinner A31 Android Mini TV Box 2G 16G Firmware 167915
Image: CSQ-A31-200W-English-20141209-1G8Gpub.img & CSQ-A31-500W-English-20141208-2G16GBPUB.img
Model： CS918S TV Box
Image file size: 421 MB / 421 MB
Platform: Allwinner A31
Build number: mars_gc2035-eng 4.4.2 KOT49H 20141209 test-keys / mars_A31-eng 4.4.2 KOT49H 20141209 test-keys
FW version: v4.4.2
Pixels: 1280 x 800
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.