DFU Programming

Hi

I would like to be able to reload the firmware to my arduino mega 2560 rev 3

I found this website: Arduino - DFUProgramming8U2

Under "Reset the 8u2" it says that you have to "briefly bridge the reset pin with the ground", and shows an example picture of an UNO. How do I do this in MEGA?

I tried different things already but I never could verify that this was working: "To verify you have reset the 8u2 chip: In the Arduino programming environment, check the list of serial ports. The serial port for your board should no longer show up."

my board is always there. why am I failing?