Update HP ProBook 6475b production model BIOS

Hello.

Can someone please help me update the BIOS on an HP ProBook 6475b I found? The problem is the production model BIOS version is 5.4A, dated 16/02/2012. I can't seem to update the BIOS because of the version mismatch, e.g. instead of F.64 it reads it as 5.4A. Tried using HPQFlash and the pre-boot BIOS update. ROM Family is 68TTU. Would like to update to F.69.

Thanks!