Replaced hybrid battery 7/2025. Big red triangle today.

Hello there-Wise Prius owners,
Whether or not it was a good idea, last July I replaced the original hybrid battery in my 2005 Prius sedan because we only had 150,000 mi on the clock. Subsequent to that replacement, we had an incident of red triangle that turned out to be a loose wire connection to the new hybrid. We also replaced the regular battery in September. This morning I got into the car and got the red triangle of death. It's the weekend so there's nobody to call. If anybody can give me a hint what the red triangle might indicate, I would appreciate any insight! And if anybody has had repeated issues of red triangle and has thoughts about whether I should continue to throw money at a 21-year-old car, let me know. Thanks!