Where did you copy gmapsupp.img file on internal memory of Colorado 550t or SD Card? If img file is on internal memory, then use UNIT ID for unlocking, otherwise use CARD ID - case when img file is on sd card!
Use JM keygen 1.5 with checksum fix from link bellow, and follow instructions
JetMouse Garmin Keygen v1.5 with Checksum Fix
Requirements: Runs on PC only.
Overview: There is a checksum bug in original JetMouse Garmin Keygen (Garmin Unlock Generator) versions 1.3, 1.4 and 1.5 which generate invalid unlock codes for some map IDs such as 2040 to 2047. This release fixes the bug by a binary patch to v1.5. Enjoy!
More Info:- Patch made by syzygy.
Download, Instructions:[Please Register or Login to download file] on jetmouse keygen v1.5, put either the 10 digit gps - unit id number (will be unlocked only in your gps) or the sd serial - CARD ID (it will be unlocked in any
gps you put the sd card
under select map product, on the bottom, custom map set, add the maps FID, also called mapid, for this mapset MAP ID - FID = 2043
click generate a few times on the bottom, all those numbers will unlock the map, copy that 25 digit number into the gmapsupp.unl file, don't add a enter, just 25 digits on the first line.
On a sd card create a garmin directory, in that directory copy your gmapsupp.unl file (unlock file) and the gmapsupp.img (g2 map)
When you save the .UNL file in Notepad, be sure you set the "Save as type" to "All Files", not "Text Documents". If you used internal memory of your PNA, then you'll copy gmapsupp.unl to internal memory - Garmin folder, in this case for unlocking is used UNIT ID - unlocking just for your Colorado 550t.