Could you try once more in the Developers Tool Kit and use the bottom input box and enter:
MAX_DISPLAY_RESTRICT_ENTRIES

then select Admin from the dropdown and click SEARCH ...

Does the:
MAX_DISPLAY_RESTRICT_ENTRIES

come up in any file(s)?

It sounds like you did not upgrade the files in the:
/admin

directory on your server ...

Check that you did not create a directory:
/admin

in addition to your renamed /admin directory ...