Remap the function keys on MS Natural Ergonomic Keyboard 4000 to ALWAYS be function keys.

fix-microsoft-natural-ergonomic-keyboard-4000.sh

#!/usr/bin/env bash
# Copyright (c) 2019-2020 Thomas Hellström <rel@xed.se>
#
# This software is released under the MIT License.
# https://opensource.org/licenses/MIT

cat <<EOF | sudo tee /etc/udev/hwdb.d/61-microsoft-natural-ergonomic-keyboard-4000.hwdb
#: ============================================================================
#: Microsoft Natural Ergonomic Keyboard 4000
#: ============================================================================

evdev:input:b*v045Ep00DB*
#  ----------------------------------------------------------------------------
#
#  Remap the utterly USELESS secondary function keys to act as normal function
#  keys. (Seriously, Microsoft, what were you smoking?)
#
#  help  => f1
#  undo  => f2
#  redo  => f3
#  new   => f4
#  open  => f5
#  close => f6
#  reply => f7
#  fwd   => f8
#  send  => f9
#  spell => f10 (This one is impossible to remap with xkb without this hack)
#  save  => f11
#  print => f12
#
#  ----------------------------------------------------------------------------
 KEYBOARD_KEY_c0095=f1
 KEYBOARD_KEY_c021a=f2
 KEYBOARD_KEY_c0279=f3
 KEYBOARD_KEY_c0201=f4
 KEYBOARD_KEY_c0202=f5
 KEYBOARD_KEY_c0203=f6
 KEYBOARD_KEY_c0289=f7
 KEYBOARD_KEY_c028b=f8
 KEYBOARD_KEY_c028c=f9
 KEYBOARD_KEY_c01ab=f10
 KEYBOARD_KEY_c0207=f11
 KEYBOARD_KEY_c0208=f12
EOF

# Update udevadm
sudo udevadm hwdb --update
sudo udevadm control --reload

# 'Unplug and replug' the keyboard
for X in /sys/bus/usb/devices/*; do
    idVendor=$(cat "$X/idVendor" 2>/dev/null)
    idProduct=$(cat "$X/idProduct" 2>/dev/null)
    if [ "$idVendor" == "045e" ] && [ "$idProduct" == "00db" ]; then
        sudo sh -c "echo 0 > $X/authorized"
        sudo sh -c "echo 1 > $X/authorized"
    fi
done

# Sing a happy song!
cat <<EOF


===============================================================================
     Installation done! Your function keys are now working as intended.
===============================================================================


EOF

Worked like a charm. Many thanks for this.

Microsoft makes great hardware, but they manage to mess up even the bit of firmware that runs on it.