Hi Abhishek,
What does /usr/sap/SID/users/sidadm/JdbcCon.log say?
Ensure database is up and so is the listener. Also check using tnsping is you can reach the database though that doesn't seem to be the problem.
Make sure that jvm is properly deployed. Just to confirm if this is JVM problem revert back the old jvm and then re-try the start.
Also check if you have followed steps of note 1810884.
Regards.
Ruchit