Hybrid Battery replaced 4 times, "Check Hybrid System" Lexus CT200h

I own a 2012 Lexus Ct200h, and when I bought it at 159k mi, I had to replace the battery.
I went to a local mechanic, they had refurbished hybrid batteries, so i had it replaced.
After about 100 mi, the Check system light comes on. I take it back. They replace it again.
Same thing happens after about 100 mi.
They replace it, then it happens AGAIN.

At this point, I am through thinking its them giving me bad batteries, and threaten them with small claims etc. They decide to drive over to my house and replace the entire battery(since i live far away from them). I personally see them take out my entire battery and they put in another one. So its not like theyre replacing singular modules and saying they replaced the whole unit.

After about 100 mi of them replacing it, hybrid light comes back on.

They kept telling me in the past they see "older" cars that have electrical issues, and he thinks theres a problem with the electrical current through the battery to car?
Is this a real thing or is he just really bad at refurbishing batteries and is blaming it on my car?
Im going to be taking it to a dealership or a certified hybrid mechanic and see their thoughts. But at this point, im just going to drop the extra 2 thousand dollars on a new hybrid battery and take these guys to small claims if it turns out there isnt an electrical issue like he is claiming.

What are your thoughts on this?