I've got my 16 GB 1,8'' 4th Gen MP3 MP4 USB Player. When I was connected it to PC, command lsusb in my SuSE Linux show: ID 10d6:1101 Actions Semiconductor Co., Ltd D-Wave 2GB MP4 Player / AK1025 MP3/MP4 Player.
I try to change the flash capacity. You may see here http://articles.softportal.com/article-487.html.
No effect. Fdisk report about mistake.
I think we need another firmware. There is china site you can find some firmware: mp4help.
But I don't know is firmware correct.