A technician is advised that a laptop battery is no longer charging. Which of the following is the BEST way to begin diagnostic testing for a battery?

Unplugging the power supply only confirms the laptop cannot run on battery alone but provides no diagnostic information about why the battery is not charging.

Most laptop BIOS/UEFI interfaces include a built-in power or battery information screen that reports the battery's current charge level, health status, design capacity versus actual capacity, and whether it is being detected at all. This provides immediate, non-invasive diagnostic data without disassembling the laptop or using external equipment. It is the most efficient first step because it can quickly confirm whether the issue is a failed battery, a faulty charger, or a firmware/software problem.

Testing with a multimeter requires removing the battery and measures raw voltage, which is a later-stage diagnostic step after initial BIOS inspection has been performed.

Removing the battery and running on AC power confirms the AC adapter works but provides no information about the battery's condition or charging circuit.