Hybrid battery pack. What is this telling me? Which cells are bad or is the whole thing bad.

Pack voltage is fine. Blocks 7 & 8 are starting to show their age, though. Grid charging with a Prolong or Maxx Volts might bring them back into line. Just replacing one or two blocks is called "whack-a-mole" since you'll be doing it again and again. The best solution is a new battery or a new set of cells from someone like @2k1Toaster if they have them in stock.

 

P0A80 indicates a failure of at least one of the cells in one of the blocks in your battery. If the code reader includes descriptions, it will say, "Replace hybrid battery pack." There will be another code that tells you which block or blocks has/have "become weak."

Sorry for the grim news, but it's time for a new battery. You might be able to drive it for a while by resetting the codes, but at some point in the near future you will be sitting by the side of the road (maybe in bad weather and/or an unsafe location) wishing you'd replaced the battery sooner.

It is remotely possible that corrosion in the battery connections or sensor wires could cause this, but it's almost always one or more failed cells.

Here's a pretty good explanation.
P0A80-Replace Hybrid Battery | Hometown Hybrids

 

Have you clean the hybrid fan? And checked the filter to make sure it's not clogged?
And make sure the fan is functioning?