Cannot log into eve-ng pro after applying license

[wlbrian]

Hello I'm setting up eve-ng 4.0.1-16-PRO on a Dell poweredge r730 with 2 x Xeon CPU E5-2667 v3 @ 3.20GHz and 768GB RAM. There is plenty of free disk space.
Everything worked fine until I bought and applied the license, which seemed to take fine. At that point I restarted the server via the "reboot" command at the console and now I am unable to log in.
If I put in an incorrect password, I will get the standard error, but if I put in the correct admin password I get nothing on the screen, and an error about the API being inaccessible in the javascript console ("Failed to load resource: the server responded with a status of 400 (Bad Request)" /api/auth/login:1 "Failed to load resource: the server responded with a status of 500 (Internal Server Error)" "Unknown Error. Why did API doesn't respond?" from loginCtrl.js)

I'm not really sure where to proceed from here...I've tried the "can't log on" section of the FAQ, and none of those seem to have made any difference.
This is the second eve-ng pro setup I've done, and I haven't had a lick of trouble with the previous one, and this is one of a number that we are looking to stand up, so I'd like to figure this out asap so the project can continue.
Any advice would be appreciated!

[Uldis (UD)]

Do again
apt install --reinstall eve-ng-pro

if it does not help come to EVE Live chat helpdesk
https://www.eve-ng.net/index.php/live-helpdesk/
use gmail to join

[wlbrian]

Sadly, that didn't fix things, either before or after reboot. Same complaint about the API not responding
I'll try to get on the chat for more help

[wlbrian]

To close the loop in the forum: Live help got me back up and running with a package uninstall/reinstall and mysql DB reload
I didn't have to do a full OS level reinstall and my license wasn't affected.