I have a 1998 slk with an alarm issue. The key fob will lock the doors and set the alarm but it will not unlock the doors or turn off the alarm. I can unlock with the key but the alarm will still go off unless I turn the key slowly a few times in the lock. Any help would be greatly appreciated

The PSE pump (which controls the alarm and locking) is in the trunk-they tend to leak water and the foam around the pump holds it in and corrodes the connector- have a look at that!!