Unless someone else here can walk you through these specific BIOS update complications or knows Acer BIOS updates well enough to advise you, I would call Acer tech support to help you as this is one operation you cannot get wrong.

If you have already tried a clean reinstall to zeroed HD, tested memory and HD, swapped cables, cleared CMOS, tried each SATA controller setting (first AHCI, then IDE) and all other steps given, then the only thing that is still missing is the BIOS update which can't be ignored as a suspect.

If you have not tried any of these fully and to completion with results noted, then ask back for further info if needed.