Did you try a new battery? The number of days are in the range you can wear out a battery. The battery is a 300 cycle rated model and the cycle count looks incorrect.

You also wrote you pulled out the laptop to use, then decided to apply the charger. That sort of use can wear the battery fast as many laptops sleep by default so if you close the lid or press the power button the battery is slowly drained as it's not plugged in, wearing out the battery in just a year.

So between the report and the story I'd try a new battery.