I see it has been a few days and I just wanted to follow up to see if you have any more questions concerning this issue or if the issue was resolved?
I only ask because based on the AGE of the device, repair would most likely be rather costly - if available at all (from an independent shop).
So if you are looking to replace the device with the same model, I would recommend looking online, at places like eBay. I have a link below to a search I did there and that does appear to be a few of these units available.
But if you are open to replacing the device with a newer model, I would recommend starting a search at places like Amazon, with the search phrase "handheld GPS waterproof", or something like that. Below is an example of such a search.
I look forward to any further questions or results that you may have.
Thanks, ***** *****