If you're looking for the firmware "t59b v5.1-8", here are some steps you can take:
Based on release notes from manufacturers using the T59B core, V5.1-8 focuses on three pillars: connectivity stability, boot performance, and audio latency. t59b v5.1-8 firmware
If you have kernel source (Rockchip BSP 3.10): If you're looking for the firmware "t59b v5
export ARCH=arm
export CROSS_COMPILE=arm-linux-gnueabihf-
make rockchip_defconfig
make menuconfig # customize
make -j4 rk3128-t59b.dtb # or specific dts
make -j4 zImage
Output: arch/arm/boot/zImage and arch/arm/boot/dts/rk3128-t59b.dtb t59b v5.1-8 firmware
Replace in boot.img using Android Image Kitchen.