Loud electronic crackling/buzzing sound + screen flickering after being charged for some hours

[Huffer]

You were only showing a charge on 1 cell now 2 are showing a charge. The battery is degraded to about 60% of its original capacity:

Primary_DesignCapacity: 5350mAh

Primary_FullChargeCapacity: 3264mAh

All models use the same diagnostic software so the test can handle up to 4 battery cells. And yours is a 2-cell battery so if its showing charge on 2 cells that is better than one. 

The battery is ready to be replaced. Whether it is also a bad AC adapter I doubt. You ran a test on the AC adapter, right? 

[chinmay_p]

The AC adapter is fine, it is passing tests everywhere.

What should I do regarding battery replacement under warranty? Should I open a new thread under the warranty section? Because I am not even sure whether the warranty that is still valid covers battery or not.

[Huffer]

Me either. There is no warranty section of the Forum that I know if you need to go initiate a warranty claim through another part of the HP site. 

Did we establish where you live (country)? Procedures vary a bit depending on that. 

[chinmay_p]

That would be India. It seems there is a 90 day period for battery replacements usually mentioned in many other threads. Which also say that it is replaced only in the 1st year, not in the extended period.

But before we go there, have we established that the battery is working fine although with only 60% capacity?

If so, then where does the buzzing sound come into the picture? It is buzzing because the battery is at 60% capacity?

In most of the threads, battery issues are always first diagnosed with suggestions to update BIOS. Should I update the BIOS? 

[Huffer]

I think I said it would be a good idea to update the BIOS as long as it is not suddenly shutting down which you said it is not. 

I still think the battery smart chip is defective and the sound you are hearing is the battery trying to overcharge itself. In other words the gate is open trying to let in more electricity to a place that cannot accept any more so you get some weird sounds and anomalous activity like screen flicker. 

So if you update the BIOS it has a very small chance of making a difference and if it does not I would replace the battery. If it still does not work right unfortunately it has to be the charging circuitry on the motherboard.