Manager styles/scripting missing after upgrade to 2.3.3

I've just run an upgrade on my site from 2.2.14 to 2.3.3, and when I head to the login page, it seems that there's something wrong with the styles or the javascript or something - I can't work it out. I've tried multiple reinstalls, most recently disabling the css/js compression with no difference in the result. I've attached screen shots below of the results.

I can log into the manager without issue, but once there I can't do anything. The main menu is messed up, the resource tree is missing entirely. Developer Tools shows all requests to the connectors folder results with 404 errors, though the connectors folder is present and accessible.

Site front-end seems to be functioning for the present, though I've not yet been able to update any of the extras that require upgrading.

That's about as much info as I have at the moment. See attached images for more info.

Please help - will answer any questions as requested.

manually delete all the files in core/cache folder. becuase you have changed environments it looks like that may be old instances still in some of the configuration files shown.

Also, clear your browser cache and cookies. A leftover cookie can mess up the Manager.

If you transferred the new files individually with FTP, you may also have a missing or corrupted file. It's fairly common with that method.

Thanks guys. I clear the cache numerous times (didn't try the browser cache/cookies thing tho Bob, I'll keep that one in mind for next time). Solution in the end required the following steps:

1. delete everything except the assets folder
2. backup then empty the database
3. upload everything into place (I use cpanel File Manager to upload and extract the zip into a separate folder then copy/move the extracted files into place - hasn't been a problem in the past. Maybe someone could confirm for me that File Manager overwrites files like FTP)
4. run setup for a new install, leaving the setup folder in place
5. empty the database again and repopulate with previously backed-up tables from old installation
6. run setup for an upgrade install
7. upload package zip files to core/packages/, and reinstall individually in Package Manager
8. delete setup folder

I've had to use that procedure a number of times before, and have the process down pat. Occasionally something happens to a MODx site that makes it unrecoverable - performing a fresh install by deleting the files seems to be the most reliable way to remove whatever is faulty. Unfortunately it also means that there is no way of knowing or correcting the fault.