Mega wont go into DFU mode

[sprinterman]

Hi,

Problem Ehtermega not going into DFU mode:

I have an UNO going into DFU mode fine. But I just cannot get the Ethermega to do it. Please help.
I can see the ethermega on the device manager of Windows 10. I short the two end pins (closest to the edge of the board nearest the port to the USB port for host connection in the group of 6 pins). When I short the two wires (like I do with the UNO), windows 10 plays a sound and the device manager blinks but then' Freetronics 8U2 USB' re-appears again in Device manager. And if I run the TurnIntoJoystick.bat and it runs the Atmel Flip program, the Flip program cannot see it (and stupidly asks me if I have downloaded the Atmel Flip program and if the Ethermega is plugged in.)
Can you please advise me what to do?
I am getting desperate.
This is my first use of the Ethermega. (Although I have had it a while.)
If it broken and there is no alternative, how would I use the UNO to bypass my problem?
Hope you can quickly give me some advice that will solve the problem.
Thanks
David