@Carlos_DobleC I completly understand what you mean. If you have no soldering experience, soldering the points on the wiiU can be very difficult.
This is what I suggest:
If you cant find anyone who specifically does WiiU repairs, try and find a local shop in your area that repairs other electronic equiptment like TV's e.t.c
Remove the WiiU board yourself, get the teensy yourself and take in some detailed pictures and detailed info of the wiring that needs to be done.
If you explain your situation to them and they understand exactly what need to be done they might do the job for you.
They might not want to do it but there is no harm in asking around. It's worth a shot if you don't want to try it yourself.
If you do want to try it yourself, here are some tips:
Make sure you use single core KYNAR wire. just search on ebay for "360 mod wire" and you will easily find some.
If you try and use regular muliti core wire you will find it more difficult.
Make sure you use some flux on the board when you are soldering, this will also make it a lot easier.
Get the finest needle tip soldering iron you can find the smaller the better and also use fine gauge solder.
Use a good magnifying glass or magnifying glasses.
Use a multimeter to test the connections.
When it comes down to the soldering itself, look online for soldering tutorials.
Before you attempt to solder to the WiiU practice first on some old electronics circuit boards first.
It can be anything. If you dont have anything around you want to sacrifice just look online for an old broken phone or something electronic thats cheap.
Good Luck.