Can't access back-office - ConnectionException - multistore

[GeGShop]

Hi! After accidentally placing the second Multistore in the Store Group of the main store, I cannot access the back-office anymore, the shop gives a ConnectionException and PDOException.

As far as I can find, these are related to database access from the website itself, but I keep going circles when it comes to solving the problem.

The front office is online and functions as expected, but I cannot access the back-office anymore.

Errors are:
"ConnectionException - An exception occured in driver: SQLSTATE[HY000] [1045] Access denied for user 'xxx'@'localhost' (using password: YES)"
"PDOException - SQLSTATE[HY000] [1045] Access denied for user 'xxx'@'localhost' (using password: YES)"

I've checked the password over and over, but I can't find any incorrect password entries, and when I change any passwords it has the expected effect: the front office goes down.

Any pointers to where I should look?