Need help to flash Lenovo Y470 model 20090 BIOS

[CDOACC4]

Hi thanks for reading. I need help to flash a Lenovo Y470 Machine Type 20090. Problem with current BIOS is that it's partially corrupted and from BIOS, the model and serial number reads as "INVALID". This became a problem for me to use Lenovo System Update as it doesn't recognize the model anymore. I tried with instructions from "https://forums.lenovo.com/t5/Welcome-FAQs-Knowledge-Base/How-to-flash-InsydeH2O-EFI-under-DOS-enviroment/ta-p/278406", but failed. Error Not support AT-p information CL Registry:0x2