Question

how to active transfer file mode of S10

Answer 1

please ignore the drow-down bar to active the transfer file mode .As default ,file transfer mode is off .You need active the usb mode and develop option ,then active the setting->system->advance->developer options->default usb configuration->File Transfer 
please refer the video :http://service.telpo.net:8091/index/user/fetfile?key=BC5ID4hKnuNMiZY0
if still not work ,please install usb driver or change other pc 
DriverAssitant_v5.1.1:http://service.telpo.net:8091/index/user/fetfile?key=kmGFrLeoRDXP6fu0

You can refer the guide via other methods to download the file ,such as from browser ,wifi adb ,adb push/install command,tf card,USB flash disk，FTP and so on.http://service.telpo.net:8091/index/user/fetfile?key=DHdvEwGlpx89IKYM