Question Radio blinks
This means without the code the radio is useless, and hence they tend not to steal it.
It will not drain the battery
If you cannot find that I would contact the Mercedes dealer with your VIN and see if they can help.
Failing that, there are places which decode/hack into them if you simply cannot get the PIN number.
Even places on ebay do it, but you need to pay postage there and back.




