Thanks. I was able to find out the solution for this.
On replacing the Essbase security file, the credentials for admin user is no longer valid which i provided during installation. In that case the admin/password works.
I was able to connect to essbase using EAS and then followed the following steps:
1. Login to Shared Services and delete the EssbaseCluster -1 under Applications
2. Externalize security from EAS to change it to shared services mode
3. Restart the services once.
It worked !!!