Should have mentioned I manually charged them to 4.2 which took a couple hours or so at 1A and they took an external load ok, pretty sure the cells are healthy enough to run the unit.
Its good practice to bring cells back up to ~3v or so at a low current (50-100mA) before charging them at 1A. Then again, its also bad practice to use cells that have spent time below 1.5V so...
I'm not one of those people who like sowing fear about every lithium battery someone asks about, but these sound like ones to be cautious about.
As others have said, the pack has almost certainly perm-failed itself. There is software out there used by battery pack refurbishers that can reverse this condition, but it doesn't work for all packs by all manufacturers, and generally isn't priced for one-offs.
You might be able to hack it yourself. The packs just talk over SMBus using the Smart Battery Standard protocol. My sig links to a half-assed arduino project to read out pack data. The reprogramming commands are often proprietary to the chipset or firmware, and generally locked by a passcode. With enough determination, you might be able to round up the necessary information from public sources, though it would probably be easier if you can read and write in one or more of Chinese, Vietnamese and/or Russian.