Inspiron 7537 beeps 5 times even after replacing the CMOS battery

Hi, 

I have a 2 years old Inspiron 7537, it is working perfectly and out of warranty.

It beeps 5 times in Dec 2016 and I sent it to a shop to replace the CMO battery. it fixed the issue.

Then on Jan 2, I drained the laptop battery (not CMO battery) during a trip. It now continues to beep 5 times again.

Should i replace the CMO battery again or it is something else ? i drained my laptop battery a couple times before but don't think it will do anything to the CMO battery.

I did all the possible dell diagnostic and they all passed.

I can replace the CMO battery again but just want to make sure that i am fixing the root cause.

May I please have your comment.

Thanks!