Hi Iyyanar ,
Since you mentioned that Controller Firmware is latest. (Version:7.00 (9 Sep 2019)
Make sure you have te Latest Smart Storage Administrator installed
> Please check the Status in Smart Storage Administrator If you are getting the option to Re-enable the Cache .
> If Battery status is Ok , possible issue is Cache Module itself .
> Since Battery is Ok ,if the problem persists, you need to replace the control card. because the cache module is embedded.
Regards
HPE Employee