Upgrade problems from 11.4.1 to 12.1.1

So i tried to upgrade from 11.4.1 to 12.1.1 and had quite some issues.
Im not sure where the problems actually were but it got stuck with the "updating in progress" message at the login window.
I made sure www-data:www-data owned everything and had 755.
I ended up deleting the MAINTANANCE file and executing the sql files manually (i just removed the ${prefix} from the content, because i have no prefix, and executed everything).
Now, im woried that maybe i did some changes i shouldnt have (or maybe add some rows multiple times).

My question is this: is there anything i could use in order to make sure the database structure is consistent or correct (the rows as well).
Or i just need to watch the logs ?