Non-running Prius. Good Buy or Not?

New to forum. I'm a 34yr old Toyota guy. I do my own maintenance on our 06 Tundra, 05 Sienna, and 09 Corolla. Every now and then I browse the vehicles for sale in my area to see what the market is like. I ran across this:
2010 Prius. Black exterior. Grey leather interior. 155k miles. Non-running and he's asking $3,000. He doesn't want to mess with it. Vehicle was being driven and then died. Driver pulled over to the side and had it towed to his garage where it has sat for more than three months. The guy is from Sudan and not mechanically inclined. (I don't profess to be a pro either, but I DO love saving money by doing everything myself). I'm only the second person to have ever gone and see the car(which aesthetically is in GREAT shape) because the owner had no pictures in his listing.

I brought my little jump starter battery pack with me, a multimeter, and my BLUE DRIVER OBD II scanner when I went to look at it. The 12v battery had only 8.8V when I first measured. Once I put the jump starter on the correct terminals, I was able to get the 13v needed to the car, and was successfully able to get dash lights and the car into Neutral position, but was unable to jump-start the car. Guessing the traction battery was dead, I assumed the car engine would turn over to remedy that but it didn't. Dash says "Check hybrid Battery" which I also believe is displayed even when the 12v battery is dead. There was the yellow triangle on the dash, and the check engine light, but I couldn't see any codes on my obd scanner! (Maybe my Blue Driver just doesn't work..i'll continue reading the forums for proper tool). I pulled the car fax on it. It was taken to a toyota dealership in Oct of 2019 where I did verify they checked the hybrid battery tested good. This service check was just before the car died on the side of the road.

My gut feeling is this is a simple fix really, I just don't know what it is. $3k is a steal for this car from what I can find online in my kansas city area, and it would be a sweet upgrade from my Corolla. I want to jump on this but am looking for that "fatherly consent" from any other prius owners out there. If majority believe it could be something serious (i've read piston rings can go bad on 2010 models), I'll just be patient. Your thoughts? Jokes? Favorite cookie? And if I DO buy it, I'm most certainly going to share the experience on here for future data collection.

 

Fantastic support! Thank you all for your help.
1. J0V - UPDATE PWR MGMT & MG ECUS - DONE on 4/24/19 -pulled from Toyota website. Multipoint inspection done but no extra notes.
2. On 10/18/19- the car was taken to a 3rd party semi-large auto shop. Engine/powertrain computer/module checked. I called that business and they shared that they checked the hybrid battery bank-and it tested fine. All they did was replace the 12v battery. He drove the car for 10 days he said with the new 12v battery then the car failed and he pulled off the road. Towed to buddies storage.
3. According to the carfax, the oil has been changed every 10k-ish miles. Sometimes 7k miles between changes.
I'm comfortable changing out the hybrid battery myself if it comes to that.

Not much other background yet on the vehicle. The guy is really nice, but from Sedan. His English is hard to understand and his vocabulary is limited. Next time I talk to him, I'll ask him pointed questions about what he felt/heard when he pulled over on the side of the road. He is no mechanic. He has no tools or experience. The car WAS taken and dropped off at one of his friend's properties which is a garage. But the business doesn't look like it's been "in business" for some years as there are holes in the roof. Basically it's a storage building for 'stuff.' Lots of other things besides a few cars in the garage. I'm guessing it was just a space to store it as the owner lives in an apartment. He originally purchased the car for $7k back in 2018. Running, the car estimates value at $7-8k on edmunds/kbb n' such for my zipcodes.

From your comments:

1. I'll need to sit there while the 12v battery charges. I have a car charger, and thankfully there is power in the building where the car sits.
2. Once battery charged up enough, plug in Blue Driver OBD scanner, and use Dr. Prius app to check status of hybrid battery.
3. If dead, shouldn't the car recognize this and start the engine to charge the traction battery?
4. But since there is the yellow triangle on the left side of dash, i'm assuming the car won't start anyway. I'll check for codes again, clear codes, then unplug 12v battery from car for a few minutes. Reconnect battery and try to start.

Out of time for now, and I'll report back. Thanks guys!

 

Update:
I finally got to speak with service dpt of Toyota dealership that did service on the 4/24/19 date. They indicated from the multipoint inspection that just several bulbs were burnt out(typical), and recommended fluid changes of engine coolant/brake fluid change...basically the typical maintenance schedule items. They noted there was nothing wrong with the car at the time.

I followed up with the owner. I asked him about the experience of when the car died. He said that he saw the yellow triangle and took the first exit closest to him. Once pullled off into a parking lot, he then had the car towed. He confirmed that there was no vibration, engine knocking, no high temperature lights or anything of the sort other than the yellow triangle light. He said his last oil change he did at 3k miles. I'm headed over today after work to do the battery charge up and see if I can read some codes.

 

Just checked out the car again tonight.
12v battery voltage prior to charging: 8.24V (oddly low..more later)
Attached my car charger. Normally it would show it's applying 14V to a 12V battery while charging. It only showed 11.3V.
I left it charging till the charger indicated the battery was at 62% charged. it never went past that point. Also strange. There were no codes at all except that the Dash monitor indicated still "check hybrid system."
After 20 min of no change of battery charge state, I unplugged the charger, and disconnected the 12V battery from the car for 2min.

Upon reconnecting the 12v battery back up, I reconnected my car charger and this time set it to "start vehicle." The yellow MIL triangle was off! The charger showed applying 17V(normal for this charger in jump start mode). I went to start the car. The engine turned over for like 1/2 second! But didn't turn on. Turned car off. Tried to start it one more time, and still, it acted like it wanted to, but felt like it was just too sluggish to continue turning over enough to get the motor running. Yellow triangle MIL light re-appeared and wouldn't turn over after that. The 12V battery never read more than 11.3 volts even after charging. I just don't think a 6 month old battery would read 8v initially unless there was a bad cell. Just really strange. "check hybrid system" was back as well.

The guy agreed to take the 12v battery back to Toyota dealership to get tested for bad cell (84 month warranty). In about a week I should get the new OBDII blue tooth dongle that will sync to Dr. Prius app( as the BLUE DRIVER dongle is proprietary..bleh) and then check the hybrid battery sections as suggested.

Learning here. I've read that it's not the 12v battery that starts the motor, but the actual hybrid battery. If the hybrid battery is toast, it can't turn the motor over. So I guess options are charging hybrid battery(i'll have to look into that on other forum posts here), replace hybrid battery? There's no other way to get the motor on?

 

Final update: Seller won't sell less than 3k regardless. My obdii dongle hasn't come in yet that will work with Dr. Prius app. After speaking with the wife, we've decided to postpone getting this one and wait for another deal down the road. Thanks all for your help. I've learned a lot already just from reading various posts in this forum and will be more prepared for the next Prius down the road.