Don't know of an alternate charging method. The fact that it takes a few hours to charge surprises me, but that's what I've been told by the adviser. Yours probably got enough of a charge for a short time, but not enough to hold. I guess the battery is integral, and requires a new key if the battery is dead. New keys are not inexpensive.

I tried to get a new key before the warranty ran out last month, but no dice.

d

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Dan
2005 X3 3.0 White/Black/Aluminum