Hi. I recently installed hoodloader2 on my UNO r3(16u2). Now I need the DFU bootloader back. I tried avrdude to remove hoodloader2 but i couldnot. I also burned bootloader from another UNO but i couldnot get DFU mode back. What should i do?
Do you have a working Arduino as well as the one you want to re-load the U2 chip?
Look for the section titled How to flash the USB chip on the Arduino Uno
Once you have run the bootloader programming sketch (and typed “G” to upload the bootloader) it will erase the chip and replace the DFU bootloader with a copy identical to that which ships with the Uno. However since the chip is erased it no longer has the non-bootloader part of the code, which actually implements the serial interface with your computer.
To complete the process you have to enter DFU mode and then upload the serial interface code.
If you have just flashed the bootloader using the bootloader programmer sketch then it should enter DFU mode, visible because the pin 13 LED flashes rapidly.
If not, enter DFU mode by shorting together Reset and Ground briefly with a screwdriver or similar. They are the two left-most pins visible in the image above, nearest to the Reset button and below the hole on the board.
(Don’t keep them shorted, just a brief touch should do it).
The tutorial has pictures with labels and arrows, is step by step and very clear.