Change collation and character set

I want to change the character set and collation of my columns, tables, and database. So far, the only option I have is to alter each column, table, and the database individually.
However, this isn't working because there are foreign key constraints applied. I don't want to drop and recreate them, as my database is 650 GB in size and contains around 2,500 foreign keys.

Disabling foreign key checks is also not working.
Is there any other way to do this?