AEM 6.2 starting with 503 Error

First - try making a copy so you do not delete anything. I would move the files to a separate folder and then try. 

Hi Vish,

Basically Indicates sling not able to connect to repository. It may be corruption Or last install broke it.   Remove the last two entry in journal.log and verify. 

Thanks,

You get that error when the authentication bundles haven't started yet. In some cases this is just a matter of time - the start up may still be progress. If it isn't just time then there are any number of reasons why the authentication bundles might not have started. There are two steps you need to take to troubleshoot the issues:

•     Look at your error.log during start up and look for exceptions and error messages. These exceptions and error messages will clue you into what the problem is. 
•     If you don't see error messages log into felix and see if you have any bundles that aren't starting and try to manually start them and watch the error logs while you are manually starting them. 

Reference Post :- http://help-forums.adobe.com/content/adobeforums/en/experience-manager-forum/adobe-experience-manager.topic.html/forum__1qef-aem_instancewassta.html

~kautuk

Hi Vish,

Please have a look at the below thread. I did face similar kind of issue ,see if this can help.

http://help-forums.adobe.com/content/adobeforums/en/experience-manager-forum/adobe-experience-manager.topic.html/forum__mj2y-hi_all_i_havest.html

Regards

Rohit

One more Solution that worked for me is, going to your instance author/crx-quickstart/launchpad/config/org/apache/sling/jcr/repoinit.  and delete this folder. Now, Restart your Server.

Hope this helps!