how do i replace batteries in keyless entry key fob, key seems to need battery on 2001 Mercedes-Benz E320 4MATIC

I used to have a 2001 420E 4Matic, sold it. two years later I bought a 2001 MB E320 4 matic, key fob from previous MB 420 is better than E320. How do I change the one fe=rom the 420 to work in the 320?

by in Candor, NY on September 28, 2012
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1 answer
ANSWER by , December 13, 2013
go to dealership or pull out metal key at top of fob. then press the grey button where metal key came out. grey button releases the case so that you can pull it apart on sides to see batteries (there are 2) I got my batteries at dealer but I guess you can get them at Batteries Plus store also.