If after installing the new DSM 5.1 from Synology, you try to log in phpMyAdmin and find yourself with a page telling you that the service has been disabled, follow this steps:
Log in your synology and click on “Package Center”:
on the installed packages look for the phpMyAdmin app. The service might be stopped, if it is not, stop it:
And restart it again by clicking on the “Action” drop-down:
And it should work again. Enjoy!