Defect of the battery: The power level displayed on the device is sometimes inaccurate—it shows 0% even when the battery still has charge. We initially suspected a fault with the internal 18650 cells and replaced them. After replacement, the device can run continuously for about 5 hours, yet the power reading remains incorrect. The battery charging port is round, as shown in the attached picture.

This is a pre-owned item, so I can't make extensive guarantees. If you need more details beyond the information shown in the product photos, you may contact me to arrange a functional test, provided I have the available conditions to do so. Once the item is shipped, return requests citing seller-related issues will NOT be accepted, unless the item is damaged/lost during transit, or the received item is inconsistent with the photos.