ok i’m assuming the pad is connected directly to the pi and not through an unpowered usb hub which may cause issues. Also ensure your power supply is sufficient (a 1Amp good quality PSU)
Then start with a new RetroPie image 1.9.1
sudo apt-get install xboxdrv
then you need to edit rc.local with the nano txt editor:
sudo nano /etc/rc.local
add this line just before exit 0:
xboxdrv --trigger-as-button --id 0 --led 2 --deadzone 4000 --silent & sleep 1
so it reads:
fi xboxdrv --trigger-as-button --id 0 --led 2 --deadzone 4000 --silent & sleep 1 exit 0
(make sure you save it, ctrl-x and press y)
cd .emulationstation sudo rm es_input.cfg
then reboot and follow the on screen prompts.
If you follow those instructions exactly your pad should connect on reboot and the top left led should light up instead of flashing constantly. Once you have done this we can move on to the next part.