Home Garmin GPS repair is something that you should approach with a great deal of caution.
GPS devices, as a whole, are very complicated and should not be messed with unless you have a simple problem such as Etrex battery problems.
If you do suffer from Etrex battery problems, for example, the repairs required to fix it are very minor. As the problem tends to be associated with engine vibrations on some vehicles, attaching an adapter cable from your GPS device to your vehicle tends to correct it by bypassing the battery.
As the flaw is in the system design, and not a true problem with your GPS unit, this is something that you can 'fix' on your own. However, other problems, such as a broken screen, should not be dealt with at home. Only an authorized dealer will be able to replace the screen without damaging the device further.
If the Garmin GPS repair job you need done is massive, you may want to consider making use of a Garmin refurbished product. You can have your GPS unit refurbished, or sell the old one to the store and buy a refurbished one in exchange, or even a new one. While only massive problems, such as a completely failed memory chip or a broken screen, warrants this, this may be the route you need to take to get a reliable working system.
The decision that you need to make regarding the repairs on your GPS unit varies depending on the problem that you are having. If you are uncertain of what action to take and you fear your GPS system is broken, please contact your authorized on line dealer so they can assist you.