searching for this mp4's os

[manu48]

Hi,
I got this mp4 digital player. I still works but I lose its operating system somewhere along the way...
Does someone know how to find it back ? Where can I download it ? How can I put it back in the player ?
I opened it but found no serial number or manufacturing ID... Only 042530 aaa / 220mah 3.7v on the battery...

Thanks in advance.
Manu

this link seems to head to similar product : http://img.diytrade.com/cdimg/313177...26tbs%3Disch:1

1.8" high clear TFT Super slim MP4 Player 1GB/2GB/4GB - MP-42 - Neutrual or Customer's Brand (China Manufacturer) - MP3 Player - Digital

Chinavasion 2GB MP4 Digital Player - image detail - Softpedia

[manu48]

Another pic here : http://www.diytrade.com/china/4/prod...tml#normal_img

The ref seems to be : DV7J66LS6YYS

Is there any firmware that would fit in this forum ? How can I check if that's the correct firmware ?

thanks in advance.
Manu