300 SD Electric Problem

[nyko46]

After many tries and frustrations, on 04/04/15 I just finished the repair of my cluster panel which was not working after changing lights. Not working because the big round connector had the D mark broken and it was causing me to connect it in wrong position. With a help of people from this forum I finally got the cluster working again.
Now a new problem arrived: Emergency light does not work and is also causing other problems when I turn it on.
Here is what happens: with the ignition key on with the car running or not if I turn the emergency light on it will not work and it will turn the radio off instantly. It will also make the central lock system to work disorganized.
I mean; it will try to lock when it is already locked and vice versa
Radio will not come on again even if the emergency lights switch is already off.
The only way that I found to get the radio and central lock system working again is disconnecting and reconnecting several times the negative cable of the battery. It take a lot of tries doing this procedure to finally get the radio and central locking system working.
Just to give a try, this morning I was driving to work with the radio on and as soon as I turned the emergency light on my radio turned off instantly.
All fuses are good and all other accessories of the car work fine.
What can be the cause for this problem?