Hello,
We have lost too many times because of this problem.
If you upgrade from older than 4.3.x version to 4.5.4.1, you are not going be able to update BIOS successfully. Probably, BIOS update package which comes with 4.5.4.1 is corrupted. It is stucking at this point "Unpack COTTONWOOD update tools".
So that, If you are trying to update BIOS r8 to r9, you have to upgrade to middle version like 4.4.4.1, update BIOS, then upgrade to 4.5.4.1.
Best Regards,
Talha