It seems a lot of repairers will avoid iPods like the plague. Owing largley to the level of difficulty in opening them up, and then closing them back up correctly. I can totally understand this... I remember the first time I opened up a 4th gen iPod touch to carry out what I assumed would be a simple screen replacement and just thinking "well there's a couple of hours of my life I won't get back" (!) Or trying to open an iPod Classic for the first time, which is perhaps one of the most difficult devices to open, and totally damaging the chassis. But like anything else, perseverance and persistence pays off in the end. What was once a pain, becomes as simple as breathing.
There are no courses or training in this field. It's experience which matters. A whole heap of trial and error in the early days and constant self education.
It's got to be hard for new repairers popping up who are entering into the world of fixing mobile phones, tablets and media players without any prior knowledge and / or prior disasters to learn from!
So, for all your iPod Touch or iPod Classic repairs, it's advisable to use someone who has plenty of experience doing so. You can rest assured that it will come back right.
Don't throw them out either if the battery fails. An iPod battery replacement is relatively cheap and quick!