Chewed up connector

Your close up pictures are out of focus so impossible to see what happened there looks like it melted.
Unplug it and take some focused pictures of the pins.

I think that’s the ecu plug. If So and it melted that means it’s pulling big current so next thing will probably be the battery will explode if you continue to drive it. Lots of battery fires.

You can just chop off the connector and butt splice the wires together.

 

That is the plug that supplies power for closing the main relays, etc. Obviously, it's jacked up.
A broken wire there is a sure cause for the relays not pulling in properly. You can either hardwire those wires together or use a short wire to jump around the connector for the broken wire.

Looks like maybe your friend didn't understand how to disconnect it and chewed it up with a set of pliers or something trying to pull it apart, along with breaking that one wire.

If you want to fix it with a bit of quality, find a 2004-2009 in a salvage yard and grab that connector with about 6-10 inches of wire and then splice it into your harness.


The small white plug in the background is for the safety interlock.

 

What salvage yard you know has 2004-2009 hybrid battery’s? There the first thing stripped out of these cars when they hit the bone yard.

 

He doesn't need the section of harness from the battery, he needs the section of harness that is part of the car wiring. He can cut it in the area I have the heavy red arrow, to ensure he has enough room for splicing into his harness. All he needs to do to get his male plug out of the female receptacle is insert a small flathead screwdriver where I have the long skinny arrow to disengage the latch that has been chewed up. Stick the screwdriver in there and pop it right apart.

 

Here's a clean view of the receptacle. Note it only has three wires. Black, yellow and white. If in a pinch, one could easily just cut all the wires right at the connectors and splice them together (in the correct pairs hopefully). Even wire nuts would work if the wires were long enough. may even be able to get small insulated spade connectors to crimp on the end of the car side wires and slide them onto the correct terminal in the receptacle. Plenty of options if the OP is competent with wiring.

 

You could also explore an AutoZone, Tractor Supply, Northern Tool and Equipment, etc to find something like this and just splice it in. Just be sure to connect the wires in the correct order:

5 kit Waterproof AC/DC Power Female&Male 3 Pin 3 Way Cable Connector AWG Marine | eBay

 

Like I said just chop off the connector and butt splice the wires together.

 

Comical.

What do you think swapping modules is? It is the same as the Frankenstein "used/rebuilt/remanufactured/reconditioned" HV Battery packs out there for unsuspecting people to buy.

Irony replacing the ECU in the HV Battery case; that part rarely goes bad. But, replace enough parts, you'll eventually replace the one that needs replacing.

Sometimes, FREE is too high of a price.

Contact Matt at Texas Prius Battery Replacement
He might have a section of harness you need. He is reputable and is a legitimate business with a physical location!
No Scamlist (Craigslist) or FraudBay (eBay) hack.

You may want to thoroughly investigate/research unfamiliar repairs that are beyond your current skills. Most importantly, just because its on YouTube, etc, doesn't make it true; lots of misinformation and bad advice out there.

 

here.....
Starting with the battery side of the connector and going to the car harness side:

white goes to red
black goes to yellow
yellow goes to green