Latitude E6420 bios error dont boot (bios recovery method)

I power on mi latitude  and does not pass the dell logo, dont to  boot, I press F2 and F12 does nothing and gets stuck on that screen does not boot, I think is some of the bios, to probe it with other memories, hard disk and does not boot ... someone know how to load the bios via USB flash mode,  it not  boot to windows and bios is for a windows or DOS, and gets stuck in the beginning of the DELL logo