More often than not the " battery died " is actually just cold solder joints . I've done Reflow on a couple keys to make them work again otherwise the buttons also will break and that will cause malfunction. If you can open up the key check the voltage. Also did you replace the battery with an appropriate 3 volt rechargeable lithium battery


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2011 E70 • N55 (me)
2012 E70 • N63 (wife)