Update, in case it helps anyone else.
I tried removing the Cache in config. No luck. I renamed the en_US/Configuration. Reinstalled extensions.
Sporadic success on the domain in progress. I kept testing and drilling down to see what was the cause. Sometimes it worked, other times I got the freeze error of
Error in uiInitialize:
TypeError: CONNECTIONS[conn] has no properties
It wasn't consistent, but I was able to get it to fail when the _insert.php or the _update.php wasn't picking up the preceding database table name, ie, leads_insert.php or leads_update.php. No idea why the pre wasn't being added. When I tried to correct the name within DA, it crashed, but the file did get renamed. I tried over and over again to recreate the 4 pages but I gave up and just won't offer this database update to client. It wasn't a critical element, just icing on the cake to keep track of form submissions. I will be able to create a page showing all the data should the client really want a record.
And in the middle of these efforts, I often got the "can't find database" message. I tested older sites and saw this come up again and again. But, after reinstalling extensions, that particular message seemed to be on really old sites which were using a different flavor of db, not the newest Mariadb. A mystery and I hope I don't have to work on any older sites anytime soon.
BUT, because I renamed my CONFIG file I have now lost all my presets for other sites using DA. Where can I find these and can I move from an older config folder to newest one so I can use again. There so many presets that are useful when I have to update any back end admin.
Thanks for the patience with my messy explanations.