Hi there,
For this error:
Unable to send an email: There are 1 partial failures, check logs for exception reasons.
Edit dsn in your local.php manually to make it work.
It’s because your generated secret key from AWS has a least one special character (=,, …). Mautic does some weird thing with encoding those characters in local.php and even if you change back to a secret key with no special character, it will still not work.