They're dead, this is the second time this has happened, the first time I didn't open the package with the PowerCap in it for a week as I was waiting for the PCBs to arrive, that one was drained down to less than 0.6V. I noticed that after installing it and finding that the NVRAM wasn't holding its contents without power.
I measured the foam and the resistance is less than 100k across about 10mm between probe tips, it's the most conductive ESD foam I've ever encountered. The terminals on the PowerCap are only about 5mm apart and the bottom of the cell is also in contact with the foam and has considerable surface area so it puts a significant load on the battery. I wouldn't deliver parts to a customer that had experienced this even if the voltage looked ok, they've been at least partially drained, I can't present them as new.