You can find Jenkins initial password from EC2 management console System Log.
- Go to Amazon EC2 console at https://console.aws.amazon.com/ec2/.
- Chose your Instance and Click Actions → Instance Settings → Get System log
You can also SSH into your instance and find the login credential using the following command.
$ cat /home/ec2-user/credentials
////////////////////credentials info////////////////////
--- Jenkins
----- User: admin
----- Password : 622766c97c21405c9ce5a54ccad3e695
////////////////////////////////////////////////////////