Hello all,

After replacing the battery in my 2005 CL65, neither of the key fobs work properly.
Neither key will turn in the ignition nor unlock/lock the doors, etc. - Replaced batteries in BOTH fobs, LED blinks fine, but nothing.

Here's the other funky part, when connecting the battery or opening the door, I fully expected the alarm to sound... However, only the lights flash for a period of time and then stop.
I know the stopping part is normal, but could the lack of alarm siren be a key element here to suggest where to look?

Attempting to use some of the craptacular fuse box diagrams online (my manual is elsewhere), I think I checked all the fuses and even checked some for ****s and grins... All good.
Central locking via interior buttons work fine, Interior lights work, Nav/Radio/CD/Changer, Headlights, turn signals, trunk lights, seat motors/buttons (the driver's seat buttons only work with door open - feature?)

The worst thing is that when connecting the new battery, each time I open one of the doors from a fresh re-connect, the damn windows go down slightly and I can't get them back up.

I did try to search for the past couple days both here and other places online to find fuse box diagrams, key fob reprogramming, etc. and have tried a few things before asking here.
If someone could point me in the direction of the antenna booster and other fuses to make sure I looked at the right ones, I'd be extremely happy.
I must have replaced the battery in this car three times and NEVER had this crazy issue.

Thanks in advance!

 

Window probably needs resetting syncing, hold up button of window for 5 seconds, do this with all windows and sunroof. Have no Idea about the key.

 

Well, I thought I'd provide a follow-up to this as it seems to have a different origin story than everything I've searched and found on this forum and on the Internet in general.
I do have to say that as a first time Mercedes owner and buying an older Merc as one of my favorite "bucket list" holy **** cars, I was surprised with the free towing from Mercedes to the closest dealer which just happened to be Motor Werks of Barrington where I was treated really well.

There was no starting the car and I had thought that I pulled every fuse necessary to find the problem, but due to the rather conflicting and odd issues with online resources regarding fuse boxes, I neglected the box on the driver's side of the dashboard. I tapped on it and it didn't seem to be a separate panel, so I didn't pry. Since my manual was back in Arizona, I only had the love of the Internets to help and got confused between multiple models and thought the fuse boxes on the sides of the dashboard were for the S-Class, not the CL...

Long story short, I expected to be fleeced, but was presented with an odd reason as to what the hell happened.
If they would have said the siren, I would have understood that maybe the batteries died in the siren and caused a fault... Nope.. The ****ing HORN... The HORN? Really?
Now, this does make sense as to WHEN this fuse probably blew, but it just seemed weird... It was a quick fix and the car was fine. In fact, I got a few compliments on the condition and the sub 40k miles on the clock.

So, since the horn was in-line with the rest of the security system and blew the fuse when the battery was reconnected, that was the reason why.
They did try to sell me on a fix for the hydraulic trunk problem, but not for dealer prices.

HOWEVER... Not knowing whether this is a Mercedes dealer thing or not, I was surprised that I had a lower labor rate at 105/hr than the standard rape. I was happy about that, so I bought a brand new smart key since the one I had was a replacement for the one the original owner destroyed accidentally.

In short, pretty much absolutely nothing in searching the forum or the Internet provided this information about the stupid horn, but then again who knows... I was out of town in California and it isn't like I could do much about it.