Hi @maxdaplushuwu
I assume that you mean that you were told that the laptop requires a new battery, is this correct? If so, why do you "...think that was a crock of crap."? Have you proven that the battery is OK?
How long does the laptop run when only powered by the "fully charged battery"?
If not long then the battery may be failing and the charger can't do both i.e. run the laptop and charge the battery at the same time.
Create a battery report to check the status of the battery.
When you have the report, compare the Design Capacity value versus the Full Charge Capacity value shown in the report.
For a new battery they are the same value. The Full Charge Capacity value decreases as the battery ages.
You can work out as a percentage the condition of your battery by using the formula Full Charge Capacity value x 100 ÷ Design Capacity value. If the percentage is <35% it is advisable to replace the battery.
If it is determined that the battery needs replacing and if you have a HP OMEN 15-dc0030nr model laptop (as selected by you), then here's the maintenance and service guide, taken from this support webpage for the model that will help.
Go to p.45 to view the procedure to remove/replace the battery.
Search online for 917724-855 to find battery suppliers that suit you best. This is the HP part number for the battery used in the laptop. It should be printed on the battery if you wish to confirm.