You are most welcome, Suzanne!
Okay, let’s give it a shot.
First, please download this script file and store it at a place where you can easily spot it.
backup_broadcom.sh (396 Bytes)
Next, go to the folder you saved it, right click on open space and select Open in Terminal. Then type:
chmod +x ./backup_broadcom.sh
And press enter. This will make the script executable. Next, type:
./backup_broadcom.sh
This will backup all the Broadcom firmware files to your Documents/NetworkFirmware folder (it creates the folder automatically and copies the files there).
Once that is done, please download the following file.
restore_broadcom.sh (579 Bytes)
Do the same as earlier. Save it to the same folder, then enter terminal inside that folder (same as above), and type once again:
chmod +x ./restore_broadcom.sh
Do not run it yet. Now you can update your system by typing:
sudo apt update && sudo apt upgrade -y
Press enter and let it do its business.
Once that is done, reboot to see if you lost Ethernet and WiFi access.
If you have, then go to the folder you saved the script files I sent you. You will need the restore_broadcom.sh.
Open up a terminal inside that folder (go to the folder you saved it, right click in empty space and select Open in Terminal and then type the following:
./restore_broadcom.sh
This one will ask for your password, since it requires elevated privileges to copy everything back to its original position - prior to the update. However, it will automatically keep a backup of its own (which will be different than the one you made when you executed the first script).
Once that is complete, reboot your system and please let me know if your network has been restored. 