i wanted to know can i change the factory rom to a custom for better?

[Android Question]

OS Android 4.0.3

ET-800II is a newest developed OTT HD smart network TV set top box
-Telechips TCC8925 1G dominant frequency A5 structure CPU
-NAND FLASH: 4GB
-RAM memory:up to 1GB(DDR3)

kernel: 3.08-tcc #172 hkt2012

build: full-tcc8920st-evm 4.0.4 Imm76D

i wanted to know can i change the factory rom to a custom for better?
thank you