I am having problems with my 1998 C280 Mercedes Benz on unlocking the doors with the remote as well as not being able to unlock the trunk nor the the gas tank cover. I cant even open the trunk with the metal key. All of the fuses are fine and new batteries have been installed in the remotes. I located a door unlock vacuum pump in the trunk. I just need some help on trying to help me resolve this problem.

The trunk still should unlock with the metal key. Insert key, turn in one direction then push. If that does not work, turn in the other direction. The trunk lock is like an old car where you can leave it unlocked but pushing the lock opens the latch.

The remote needs to be synced with the car. On 97 model year the remote is clicked 2 x then key inserted in ignition and turned to run. Not sure if the 98 electronic key is the same.