Download Android KitKat 4.4.4 stock firmware for RK3128 device from here or from here. Download previous firmware from here.
Model： RK3128 device
Image file size: 414 MB
Platform: Rockchip RK3128 / RK312A
Model number: rk312x
Boot version: 2.20
FW version: 4.4.04
Build number: rk312x-eng 4.4.4 KTU84Q eng.foxluo.20160718.155029 test-keys
SDK version: RK30_ANDROID4.4.4-SDK-v1.00.00
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.