In regards to the alarm, there are microswitches clipped to the lock cylinders of the two front doors. Turning the key causes a cam to flip the microswitch in either the arm or disarm position (depending on which way the key is turned). These are momentary contacts. Depending on the part # of the cylinder, you might be able to order a replacement switch. In some cases you have to order the whole lock cylinder with switch, which costs more. The same problem happened with my '94 E320.

For now you can pull out the plastic cap inside the door above the latch and disconnect the 3-pole plug for the ATA microswitch. This will prevent the alarm from being armed when you lock the door.

As for the driver door not unlocking, check for vacuum leaks from the central locking pump to the driver door lock vacuum element.

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2002 E320 T-sedan (210.282) 219K
1994 E320 (124.032) 252K (dearly departed in hit & run)
1988 260E (124.026) 301K (sold)