My A123 cells are dying... help?

I also bought 6 2s2p packs from Hopmeup on ebay. Had one cell vent and pop, after doing a few speed runs in a 6s2p config with a neu 1515/1y. Other than that they have been fine, and a lot better than the other non a123 lifepo4 cells. Have since combined them to be 3s2p packs, to run as 6s2p series pack.