Last year for Christmas I bought some tiny MP-4 players on Ebay. Unfortunately most of them died after about a month of use. One sat around in my drawer until this weekend when I decided I was going to dissemble it. You should be able to remove the bottom cover with two screws then slide the guts up and out of the top. However I could not get it apart that way, for some reason, so I cut it open with a pair of tin sheers. I could not fix it or get it to work with external batteries, but that is a good thing, because I could not get it back together either!
Here is what they look like inside if you wanted to see their guts: