Please try:
1. cPanel --> MySQL Databases
Current Databases
aaa_jo151 0.00 MB aaa_jo151 X Delete Database
Click on the user
Check ALL PRIVILEGES on the next screen
Repeat for all db users
Click "Save Changes"
That should work.
2. Still no connection, check the software confinguration/settings file . It should set something like $dbhost to 'localhost'. If not, something like 'ini.chopin.x10hosting.com' , change it to 'localhost'
3. Still no connection, post back here.