You have changed the permissions of the whole database directory and that's why you can start it now. You can get the real error message from the database's log
2020-07-26T12:49:45.499285Z 0 [ERROR] [MY-010274] [Server] Could not open unix socket lock file /opt/bitnami/mysql/tmp/mysql.sock.lock.
2020-07-26T12:49:45.499404Z 0 [ERROR] [MY-010268] [Server] Unable to setup unix socket lock file.
2020-07-26T12:49:45.499649Z 0 [ERROR] [MY-010119] [Server] Aborting
Run these commands to try to set the original permissions
sudo chown mysql:root -R /opt/bitnami/mysql/data
sudo chmod 777 /opt/bitnami/mysql/tmp
sudo chown mysql:mysql /opt/bitnami/mysql/data/*
You can try to start the database now but if it doesn't start, please take a look at the log file again and try to solve all the permission issues you receive.