I changed the password of BISystemUser in Console and EM->Weblogic Domain -> Credentials -> oracle.bi.system -> system.user. Both of them were reset to same password (different from the password for the new user). I restarted the Admin and BI server but still no luck.
The principal below says CN=ADBISystemUser, this is not the user id but the user name (Fname LName). As soon as I put in the FName and LName in the principal and restarted everything, it worked !
The log had an error LDAP: error code 49. By digging more on the error I realized the error in the principal.
Host : pdc.gcbc.com
Port : 389
Principal : CN=ADBISystemUser, CN=Users, DC=gcbc, DC=com
Credential : Welcome1
Confirm Credential : Welcome1
User Base DN : CN=Users,DC=gcbc, DC=com
User Name Attribute : cn
User Object Class : user
Group Base DN : CN=Builtin, DC=gcbc, DC=com
GUID Attribute : objectguid
Thank you everyone for all the help in the most prompt manner !!