Do you have a backup of the internal files? If so check in Garmin folder for the file GarminDevice.xml and look for the HWID 0851 [shown as: <PartNumber>006-BXXXX-00</PartNumber>]:
<?xml version="1.0" encoding="UTF-8"?><Device xmlns="http://www.garmin.com/xmlschemas/GarminDevice/v2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.garmin.com/xmlschemas/GarminDevice/v2 http://www.garmin.com/xmlschemas/GarminDevicev2.xsd"><Model><PartNumber>006-B0851-00</PartNumber><SoftwareVersion>760</SoftwareVersion><Description>nĂ¼vi 255</Description></Model><Id>xxxxxxxxxx</Id><RegistrationCode>
If you have a different HWID then advise what it is. The HWID 0851 is for US/EU units with non-MTK chip.