If this could be of any help, below is the value of TWO_TASK alias mentioned in EBS application tier node tnsnames.ora:
Since Demantra is unable to find the defined connection string for the parameter "local_listener" that is provided by you (test03). Its unable to establish a session.
After change you were able to do tnsping from Demantra appln server with new string ? Have you updated in tnsnames.ora on demantra server.