Diagnosis
A blinking white light indicates the hub is in its normal startup or connection sequence. If it never settles, it's failing to complete its boot process, often due to corrupted firmware or a failed update.
How to Fix It
Perform a hard reset. Find the small pinhole button on the bottom of the hub. With it plugged in and powered, use a SIM ejector tool or paperclip to press and hold that button for about 10 seconds. You'll see the light cycle through colors. Release it when the light starts flashing yellow rapidly. This factory resets the hub. You'll then need to set it up again as a brand new device in the Aqara app, which will also push a fresh firmware image.
If That Didn't Work
In rare cases, a persistent boot loop can be caused by physical memory corruption. After the hard reset, if it still won't progress past blinking white, unplug it for a full 24 hours. This allows any residual power to drain completely from the capacitors, performing a deeper, cold reset. Then plug it back in and wait.
Heads Up
A factory reset via the pinhole erases *everything*. All device pairings, automations, and settings are gone. You'll have to re-add every single sensor and recreate your scenes. There's no way to back up the hub's configuration locally.