ok, here's from my own experience. i've gotten batteries hot enough that u could barely touch them cuz the wire i was soldering was being a biznatch and not staying put long enough for the solder to cool and harden (stupid helping hands aint always helpful
) anywayz, i had the same "dead" battery thing in two dual cell jobs. i had a dual cell charger ready to go before i even did my first dual cell mod and one battery had 0 volts the other had 1.2 volts after charging them at 6 volts (which i later found out was NOT necessary, you only charge at or
slightly above the total voltage rating, which means 3 volts for dual cells, any more and it kills the battery and heats it up) well, the solution was to cycle the batteries to try to "jumpstart" the second cell that had no voltage. all i did was charge it up, run it until it's completely dead, charge it again and i did about 3 cycles and the second cell suddenly sprang to life after the third charge and i was blazing around my table after that. so basically, charge and discharge it at 3 volts until ur "dead" cell comes to life