My iPod Melted...

Hi, I bought an iPod 5g about 9 months ago, 2 months ago the battery started acting up (it would not last more than 24h when turned off...., it would lose its charge) so i brought it back to where i bought it (Fnac, i'm in france) they sent it to apple france who sent me a brand new one, so far so good. However, i brought the new one home, put it into its iSkin started to charge it, and a part of it melted, so i brought it back, and now (after a month and a half) they sent it back, saying it worked perfectly fine, and that the ipod was not in cause in the melting (they said the heat source that caused it to melt came from outside) i'm obviously not leaving things like this (the heat source could not have come from outside since the case was on, and the case is fine and the spot melted is rather small (1/2 inch) and the case would have spread the heat from an external heat source much farther). I went to look up some pics of the innards of the ipod, and found that the spot that melted is right above a chip so i would like to know what that chip does (its right next to the right "arrow" on the touch wheel, a bit off to the right and up) and if anyone else has had a problem like this?
Thank you!
-Cedric