i've checked and quadruple checked my information in my wp-config file [compared it with the previous version's file AND in my CPanel DB page], it's all correct. i haven't changed ANYTHING else in the new upgrade, just followed the instructions. now all i can do is access the DASHBOARD, where i authenticated the new upgrade, but can NOT access the site itself [error 404 pages].
this is horrible.
i submitted a ticket to my host and HOPE they can help me, but if your site says "it's as simple as this" and then it's NOT, well, crap, the title "simple upload" should be changed. :/