Highway driving to reset P0A80 and P3012 codes

Hello! After sitting alone for 2.5 months, when I returned to my lovely 2005 Prius it needed a jump start. Half an hour later on a drive to further charge the battery, a bunch of warning lights came on and I took it to a Toyota dealer who said it showed the P0A80 and P3012 codes, and said that although it's probably just one cell that's dead, it needs a new HV battery.

I spoke with a non-Toyota hybrid service centre, and the guy there told me to drive it for 30min/day on the highway without stopping for a week - and that there would be a 50/50 chance of that somehow fixing the HV battery issue.

Reading other posts on this forum, I see some opinions that it's actually not great to drive the Prius much without the HV battery... and others that say to put the car in drive, press the break and the gas at the same time, and that may reset the battery.

So... I suppose I'm looking for further input and opinions on what to do! I'm also curious about the P3012 code... it makes me wonder if replacing the battery is not enough.