Update bios on system that will not boot

Hi,
I need to update the bios on a pc in my shop. The customer tried to install a 40 gb hdd on a motherboard with award bios v4.51pg. This version has known 32gb limitations and the cylinder limitation jumpers may not work according to Maxtor. theysuggest a bios update. how do i do a bios update on a system that will not boot. The original hdd that was in this oc now will not boot I get this message” CPU is unworkable or has been changed. please recheck-CPU SOFT MENU. It will not boot into meboot disk even with floppy set as first boot device.