Date registered: Dec 2005
Vehicle: W211 E320 Bluetec R129 SL500 - $1300 car ........ Ford F350 6l
Location: CA Bay Area
Mentioned: 9 Post(s)
Quoted: 1054 Post(s)
ML and E are siblings so lot of things are the same or similar.
Working on our E I left the key in the ignition for 24 hr and the battery was still good.
Even if the shop left the door open, the computer will turn the lights off after few minutes.
Other thing is that if the shop kept slapping the door for hours, that could take older battery.
I would not worry about it too much, but testing the battery and keeping an eye on voltage would be in order.
On other hand a shop who did not test drive the car after brake job would not have my business.