Even if you wipe out all keys by exiting auto registration, you can still restart a new key reseeding process. And there is no fail safe mode. It is either in registration or it isn't. The B2796 history code was most likely set due to your battery dying in the registration process. You should be able to clear it w/o any problem because it is a history code. As for which chip is which, that is not my expertise. A factory ordered key resolves this issue though. Usually. Haha. There is only one way to really know if the vehicle took the keys you tried to register. And that is to exit auto registration. It is also possible that it appears to be in a fail safe because it is still in auto registration. Once it is exited it will finally show which keys are registered and which aren't. This is just speculation but it makes sense to me. Haha