@Condobloke Thanks for the encouragement. Upgrading to Mint 20 worked on 2 of my 3 computers, so they are doing ok. The 970A-DS3P was always a pain with linux, particularly with USB support. I might give it another go with a DVD drive installed.
I also have a 970A-DS3P. I upgraded from Mint 19.3 (kernal 5.4.0-40) to Mint 20 (based on Ubuntu 20.04, using the same kernel) and it failed by booting to command prompt with no network. Booting from USB is almost hopeless and I have not tried a live CD.