Prius 2005 error codes: P3030 and P3000

I have Prius 2005 parked for around 5 months. last week I moved the car and all was good. During driving the fuel motor stop working and the car starts to limp. I stopped the car, turn it off and on again, then all warning light turn on (check engine, VCS, ABS, and red triangle). The car moved but it seems like the main battery stopped working.

I read online and I used Toyota Techstream. I got two main codes P3000 and P3030.

I opened the battery and I noticed that Block 3 is melted and disconnected from the ECU connection. I fixed it and checked voltage and continuity for all sensing wires and all are Ok. ( I measured the voltage for each cell and block it was 7.9V and 15.94V for all of them).

I connected the battery again but nothing changed and all errors still showing.

I read the voltage for each block using Techstream. The voltages for all blocks was 15.9V almost. But it starts showing a weird pattern. Block 3 voltage drop to -0.4. Then block 2 and 3 voltage drop to -15.9V then back to normal 15.9V.

Is this still a harness error? or ECU?

any suggestion or help troubleshooting the issue?

Many thanks in advance.

 

There is no one available in the UK dealer, so I ordered one from Japan. It needs a week to arrive.

But if the wire is connected, why the voltage fluctuate to zero and negative? can this be an ECU fault?