For all those who want to use Recalbox 6.0 with the GameHat, here's how to do it:
Write the img of Recalbox 6.0 on your sdcard, then from your pc, add that parameter to the "config.txt" file at the root of the card:
hdmi_force_hotplug=1
avoid_warnings=1
max_usb_current=1
hdmi_group=2
hdmi_mode=1
hdmi_mode=87
hdmi_cvt 640 480 60 6 0 0 0
hdmi_drive=2
display_rotate=0
Use winscp and notepad++, not recalbox manager.
Then connect one gamepad (wired) and fill in the wifi settings. Then via the web interface edit the "recalbox.conf" like this:
Change statement controllers.gpio.enabled=0 to controllers.gpio.enabled=1
Change statement controllers.gpio.args=map=1,2 to controllers.gpio.args=map=5 gpio=5,6,13,19,21,4,26,12,23,20,16,18,-1
Disconnect the gamepad and reboot the recalbox. After the reboot push one button and configure!