Mercedes B Klasse power windows dead after battery replacement

Sounds like a pain. I had a similar issue with my old Audi A4. Replaced the battery, and suddenly the windows wouldn't work. Did you try the window reset procedure? Sometimes the car needs to relearn the window positions after a power loss.

Window reset procedure? I'm not familiar. Is that some secret handshake I need to perform with the window switch? Do you have any further details, like maybe how long to hold the button or anything?

Yeah, it's usually something like holding the window switch in the 'up' position for a few seconds after the window is fully closed, then doing the same in the 'down' position. If that doesn't work, honestly, a trip to a workshop might be in order. They have the diagnostic tools to properly initialize the window regulator and clear the error. If the window motor is damaged, it's a different story.

Thanks for the info! Turns out it was a bit more complex. The garage hooked it up to their system, ran some kind of window regulator adaptation, and cleared the fault. Cost me 290€, but at least the windows work now. Appreciate the help!