hv battery question

Got the red triangle of death today but it went away on its own. my tech stream was messed up and wasn’t communicating. Anyway, the stereo was cutting out intermittently and I'd had the car on sitting idle for a bit so I figured it was likely the traction battery. I'm still planning to check with Dr. Prius to see about battery cell issues. When driving at highway speed, it will light up all but 1 of the battery cell marks on the energy display.

Meanwhile, I went to the junkyard and found a Gen 3 although I don't know the mileage on the battery. I did see some corrosion on maybe 9 or so small terminal nuts. This car is recently in the inventory (maybe a month or so) and has very minor collision damage so I'm thinking it may have been sitting for awhile. I removed the safety plug and the battery cover to measure voltage. I didn't remove the terminal nuts but did try to measure voltage between positive and negative terminals on several individual batteries. These all measured near zero. Does that mean it's been sitting forever or would I need to remove the small terminal nuts to measure voltage? Is the battery likely hopeless or could it be reconditioned?