So, the Protege is working now and there was nothing wrong external to the battery that caused the problem? Reason I bring this up is that if this were an internal problem with the battery, the protection circuit wouldn't have helped. It is connected to the external connections of the battery and only capable of stopping the external connections to the battery. The only internal safety in those batteries have is the pressure relief valve on the positive connector. There's no way to stop a runaway chemical problem internal to the battery.
Kevin
Kevin