Nano's arent very repairable- depends on which generation it is, but the parts are so itty bitty that they are usually all on one board- which means that to fix them, you spend almost as much as a new one just in parts.
I have fixed a bunch of ipods in the USA, where you can easily find the parts online and actually get them shipped to you.
Its not that hard, there are generally only a few things you can swap out.
Of course, its technically possible to do board level replacements of some parts, but that requires a level of electronic skill that usually means the person who does it can get a much better paying job than fixing ipods.
Here is a parts place I have used a lot- you can see which parts for your generation of nano are even available, and what they cost in the US.
Then, you simply figure that you will pay at least double, if, by some remote chance, somebody in Argentina actually had the part, plus labor.
http://www.ifixit.com/iPod-Parts/iPod-Nano
My guess is that you should keep trying to restore it, let it dry out on the off chance it got wet, and, if it really wont restart, consider finding someone who is coming down who can bring you a new one from the US or Europe. Its gonna be cheaper.
