Tearing into a bunch of 4 yr old Dell packs I kept running into packs that had one or even a few of these "0 volt - Open Circuit" cells inside. They would not accept a charge and read infinite resistance on the meter. Finding this odd I tore into a cell to find out what was happening and surprised myself running into a short circuit! In my research as to why that was happening I didn't come across any videos or easy to find ones, so here's my contribution. If you've watched videos on people trying to vent 18650's or blow them up with high current overcharges this is the device that "spoils the fun" when things start heating up. First this disc pops, but with increased pressure buildup it splits and vents. Be careful! Don't burn your house down trying to save a few bucks, you aren't going to find a really good cell that has been through this. In testing capacities after "resetting" a few cells they all appear to have lost 1/2 or more of their original capacity.