Microchip PIC24F & Android device: Which can be host device?
You will need to attempt debugging from the PIC side.

The PIC acts as a USB host.  When it runs, it should connect to the android device.

Check your code to make sure it doesn't need to be modified to specifically recognize the VID/PID of this android device.

Then step through the code and see if the USB host is connecting to the android device, and if so whether it's sending or receiving on any of the USB pipes.

I suspect it'll be an issue of configuration in the software.  The PIC ADK software lists devices it supports, but you probably need to add an entry in the code configuration file to allow it to attempt to connect to the S2.