My brother's Macbook Pro's is exhibiting a weird problem. Whenever his MagSafe charger is plugged in and connected to his laptop, it doesn't charge. I then took that same charger to my computer (without a problem) and it does the same thing. Now this is where get's interesting. I then unplug his charger from the wall then connect it to my laptop and it begins to charge. I quickly take his charger back to his computer and it doesn't start charge. I take it back to my laptop and it does the same thing (not charging even after doing so a minute ago). I observed the same thing with my charger (unplug it, charge my laptop, doesn't charge his and then doesn't charge mine until I unplug and connect to my MacBook Pro). Any ideas as to what might be the problem (dead battery)?