2016 Prius Battery Sensor repair

Greetings,

I had the Prius start sending out phantom error after its power on self test [ready check on the car as the non IT people would say]
I thought it was the battery so I changed it out with a new known good new 12v battery
The car then wouldn't turn on at all.
I went to inspect and low and behold the actual lower [bottom] sensor wire that connects to the negative battery flow sensor was disconnected. Ripped apart.
I looked further and noticed that a sections of the wiring are covered by electrical tape and not in a proper harness.
After getting some wire and soldering under great difficulty I was able to patch the actual cable and got the car out of the garage, with no error warning.
As I drive 400 miles a week I don't want to consider this fixed. I just needed it patched to get it to a repair shop or formally fix it myself.
I tried to trace that broken lower cable to see what it terminates into. I just ran into a lot of cables and confusion. I had to strop for fear of damaging more cables and not knowing what electric tape to cut.
T
these leads to a few questions.
1. What is the name of this battery sensor replacement part? Keep in mind it's not the sensor but what the sensor wiring that is damaged
2. What is the cost of a repair to get this wiring formally fixed?
3. Is it possible to DIY this wiring replacement?

[possibly part of section g92x2]
Attached photo is my prius battery connection the yellow colored area [used MS snip to highlight] is the actual wire I had to repair.
Thanks

Daniel