I am trying to replace the existing PDB with Supermicro 23-Pairs Power Distributor (PDB-PT826-8824) so that I can replace the PSUs with 1280W PWS-1K28P-SQ . However, after removing all screws that I can identify, the PDB still cannot be removed. Has anyone done this before and have a tip or two to share? Any manual/instructions will be appreciated!