ssh "permissions are too open"

if linux try chmod 400 ~/.ssh/id_rsa

That error message is local to your computer, it's not related to the EC2 instance. It's telling you that the file permissions on the .pem file are too permissive. As per the other answer, change the permissions on the file so that only you (as the file owner) can read it: chmod 400 mykeyfilename.pem