Did you launch the instance from the marketplace? If yes, your instance identifier should have a
mp identification in its name. It should be something like:
In those cases, the password is regenerated during the installation, but if the image does not belong to the Amazon Marketplace (it does not have that identifier), the password is not changed.
From your log, it seems that your instance belongs to the second case. Could you please try with the credentials below?
I hope it helps, and please, don't hesitate to write us again if you have any other question.