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If the work that was done involved having the battery disconnected at any time, the Nav. system may need to have a anti-theft code entered. (Or, if that isn't the problem, try entering a default password, in case it really was reset, such as
An activation code for a car radio or car stereo etc., is an anti-theft feature. When the device is removed from the car, the battery power is interrupted to it, and this activates the anti-theft feature. The entering of an obscure code is required before one may use the radio or stereo etc. again.
Sometimes this anti-theft feature is activated when no theft is involved, for instance:
- when a car stereo is sold, after being taken out of a car, by its legitimate owner.
- when a car's battery has been disconnected for servicing of various sorts or in the event of car battery failure.
The code is very hard to 'generate' or hard to find. It would not be an effective anti-theft deterrent otherwise. I have not the means to generate the code for you (though I believe it is generated from the serial # ***** the device and according to the maker and model.)
I advise that you take the car to a dealership for that brand, and have them generate and enter the code for your stereo.