the smart key is working just fine in the ignition.the car starts just fine.however the buttons(lock,unlock and trunk,panic)are not working.they were working fine.they stopped working,i changed the batteries,and i believe the key need to be progammed again.any help wil be appreciated

If you replaced the batteries correctly, the smartkey will program itself once you insert it into the ignition.

Proper installation of the batteries requires that they both face each other (flat side looking out on both). After replacing mine, I found this configuration sort've odd but that's how it works.

Good Luck

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-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

that's funny because there is a drawing on the plastic insert that indicates clearly how the batteries should go ,both of them facing the plus side on the same side.
i'll try your version tommorow.

Batteries assembled in this manner will have a total voltage potential of 0. They cannot work like this so don't do it.
Make sure the contacts are clean and rebend the spring clips so they have good contact with the (clean)batteries.
Always assemble the batteries according to the instructions.

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2012 E350 Bluetech