Hi all,

We are having an annoying issue with our 2006 SLK 350 where the head unit only shows the MB logo for a couple seconds, then shuts off:

I've searched around forums for weeks, trying to figure out what is causing this, but can't seem to pinpoint it yet. I've come across a lot of talk about this MOST loop that Mercedes have, and if you break any component in the series connection, it doesn't make the circuit and the radio will shut back down- which sounds exactly like my issue.

Background: We also noticed that we had water build up in the trunk area at the spare tire, because a drain was messed up- we also had a drain that was allowing water to fill up the battery compartment under the hood- yeah, i know. Initially, we were having an issue with the battery draining overnight, so we replaced the battery with new. Then, the problem kept happening right away, so we had a guy at my work use his electrician to fix this problem so the car would actually run/start. He got it to run, but i have not been able to contact "his electrician" to find out where my $600 exactly went into the (& what kind of) repair- big problem, but still trying.

Anyways, car starts up great, everything else works pretty normally to my knowledge, except the radio won't come on when you turn the car on- if you press the 'power' button, the MB logo will show for a few seconds and then the screen goes black again. In the trunk, we have the navigation (disc) unit in the center of the trunk, then a component on the left side of the trunk that you can access by pulling a velcro panel off the side wall (not sure what this is). I also notice that behind this component there is one cable that is not plugged in- not sure if this is normal either- i will try to get pics soon.

I've checked all the fuses in the driver side, under the hood, and trunk (not behind radio), and they are all fine. One question is i keep seeing talks about a #6 fuse in the trunk- but our #6 position does not have a fuse in it. Is this correct? I wish i knew which fuse locations were connected to the MOST system so i could check those locations specifically.

I am planning on getting the fiber optic bypass connector from the dealership tomorrow, but i also don't know the locations of all the MOST loop components:

1. Head unit (obviously not "working"- but is it the cause)
2. CD changer (we don't have an additional changer besides the navi)
3. (CP) communication platform- no clue where/what this is
4. Navigation- this is working- (at least the disc comes in and out)
5. Voice recognition module- no clue where this is.
6. Audio gateway- is this what i'm looking at in the trunk mounted to the left side INSIDE wall (i didin't remove the wall liner/carpet, just a little additional black fabric enclosure).
7. UCP (upper control panel) - i assume this is working because the cluster lights and eveything are working.
8. CGW? what/where is this?

If i can bypass these all tomorrow, then surely i can narrow down the faulty component? Anything i am missing?

Please assist me in this journey of diagnosing my issue.

Thanks
Kyle