Hi,
This error usually comes up when the JAR file is corrupted. We'd suggest you to check if the JAR file corrupted.
FYI: You can check if your JAR file is corrupted using one of the following ways:
1) When you try executing "java -jar cq-author-6.2-4502.jar" from command line, you should see an error indicating that your is corrupted in stderr.log file.
2) You can extract the contents of AEM JAR file using 7-zip and verify if "Main-Class: com.adobe.granite.quickstart.base.impl.Main" is part of META-INF/MANIFEST.MF file.
Hope this helps!
Regards,
TechAspect Solutions