Once that done and after testing half a dozen installs and checking battery draws in Battery Log app, I confirmed that this indeed fixes the works! Cheers!!!
After a lot of googling and searching I did not find much. But then today I hit the lottery. Found out that I someday mistakenly upgraded Google Play Services and that caused all this. Anyway, how to revert back. Big question. After fiddling out here and there, I found out that I have to search for Google Play Services in Store app, and from there I could downgrade Play Services.
So few days back I started using my Intex Aquafish as my daily driver. The phone is great at a basic phone. Calling and internet works fine. Whatsapp also works fine and so does Google Drive. That's almost all the use cases for me.But something threw a spanner in the works. I tried installing few more apps, and they get stuck at Installing screen. Then couple of days back I started seeing large battery drains by gms.persisttent.