Finally got Mint Cinnamon 19.3 working! It was a permissions problem. The solution was to chown my home directory to bill even though the directory appeared to be already owned by bill. I did this by booting Mint single user mode. At first I was under the assumption that /home wasn’t being mounted, but realized single user mode doesn’t mount drives.
bill@bill-MS-7B79:~$ ls -la /home
total 56
drwxr-xr-x 9 root root 4096 Apr 24 2018 .
drwxr-xr-x 23 root root 4096 Apr 11 14:35 ..
drwxr-xr-x 165 bill bill 12288 Apr 11 14:31 bill
drwxr-xr-x 19 bill bill 4096 Jul 31 2018 bill-new
drwxr-xr-x 36 bill bill 4096 Apr 20 2019 guest001
drwxr-xr-x 22 bill bill 4096 Sep 21 2016 guest001x
drwxr-xr-x 3 bill bill 4096 Sep 21 2016 hold
drwx—— 2 bill bill 16384 Sep 9 2014 lost+found
drwxr-xr-x 18 bill bill 4096 Mar 17 2019 temp2
bill@bill-MS-7B79:~$ sudo chown -R bill:bill bill/
bill@bill-MS-7B79:~$