How common are hardware problems with iPod 6th generation?

My iPod nano 6th generation failed a few days after the initial 3 month service ended. Because of the 1 year limited warranty I was able to return it and get a replacement free of charge. However, in less than 2 weeks the new iPod also failed. I assume that Apple will repair or replace my iPod promptly as before. but now I wonder if there is some inherent problem with the product.

In both cases I was running with the iPod clipped to my waistband. The first failure occured when I tried to turn the volume down. I got a buzzing sound and could not shut it off, even after disconnecting the ear buds. Eventually it did shut off, but would not power up or reset. The second failure was more like a battery failure, but again this was a new iPod replacement approximately a week old. The iPod was fully charged the night before and I had been using it for about an hour. I was warned that there was low power and then it immediately shut off before I could turn it off. I plugged it in for about 2 hours and went through all of the troubleshooting steps on the site, but it would not restart. I have submitted another service request.

Here are my questions:

(1) It seems possible that this product is especially sensitive to minor shaking, as happens when I run. This seems surprising, since it has a built in step counter (which is why I take it with me). Has anyone else seen this problem?

(2) It may be coincidence, in which case I was either sent a bad replacement product or a replacement with a bad battery. The service is good, but has anyone else received a replacement from Apple that has problems?

(3) Finally, are there inherent problems with the iPod nano 6th gen. that makes it a worse product than most Apple products, at least in terms of reliability? Am I just having unusually bad luck, or is this a general issue? Or, conversely, are Apple products in general unreliable (this is my first Apple product)?

Sincerely,

Tom RHoads