Removing No.2 Frame Wire: situation not matching service manual

My 2007 Prius has been throwing code P0AFA. The technician at the dealer suspects corrosion of a connector to the Battery ECU, and as best as I can tell, the relevant connector would be the one between it and the No.2 Frame Wire. Today, I removed the battery from my vehicle and opened it, intending to remove the ECU and No.2 Frame Wire so that I can attempt to clean the contacts.

I found a digital copy of a service manual, ostensibly applicable to Gen 2 Priuses in general. I can't find a page in it directly stating which year it's applicable to, but it has been exactly accurate up until this point. During the prerequisite step "REMOVE MAIN BATTERY CABLE" on page HB-103, the manual calls for me to remove the terminal nut which connects the No.3 System Main Relay to the battery cable. However, this terminal currently measures approximately 100V to the case. Similarly, the terminal nut which connects the No.2 Main Battery Cable to the No.2 System Main Relay measures about 30V to the case (I didn't note down the signs). It would not be safe for me to remove those nuts if accidental contact between the case and the tool is a 100V short. I don't see anywhere on either frame wire that is obviously connected to the case, so this might just be a floating voltage, but I can't figure out how to check this.

The step also calls for me to remove a "shield wire", but I can't identify any other wire on or near the Main Battery Cable. The associated drawing is not clear. Is it something to do with the Battery Current Sensor?

The battery in question is a refurbished battery from Green Bean. I'm wondering if they did something different from the manual when assembling.

I would appreciate any advice on this discrepancy and how to continue

 

Here are some photos for reference. Most of the nuts holding the frame wires on are heavily corroded, so I won't be surprised if I can't clean them and need to replace them.



I would also appreciate guidance on removing the Wire Harness Protector Covers. The manual does not give any instructions, and while peeling them upwards did most of them off, I broke small pieces off of both frame wires.