engine stalls after stop safely now light: hv battery issue

My daughter's 2006 Mercury Mariner hybrid has stalled within seconds of getting the Stop Safely Now engine light on, in traffic near her college. The dealer has said the codes pulled were P1A10 (Powertrain control module Bat disabled) and POA1F;20 related to the Battery Energy control Module. However the Mercury Service department has said the High voltage battery needs to be replaced, which costs $11,000 plus $450 for installation. This basically totals the car based on its worth.

The car only has been driven 40,200 miles of the 100,000 mile warranty however has gone 1 year over the 8 year time warranty. The problem is that the car will drive intermittantly and stop after a few miles, after a few minutes it becomes drivable again. This sounds like an issue with overheating of the battery, vs a battery short situation.

After filing complaints with Ford, including the zone representative, they are unwilling to even have someone from Ford Quality or Engineering review the situation, which is an anomoly. These hybrid vehicles are getting 250,000 to 300,000 miles in NYC taxi cab fleets, so this failure at low mileage is something they should investigate.

The only support offered extended was a Friends and Family new car discount, of which we would never exercise or buy a Ford product again.

If anyone has a similar experience with the 2006 Ford or Mercury hybrid, I would be interested to understand the solution. I understand it could be a bad fan for the battery cooling, the DC/DC converter, the PCM (reflashing) or battery harness module corrosion, or air conditioning related.