Hello, friend!
The B628-350 is a consumer device, and we're sorry we can't provide you with the firmware for the device.
According to your problem description, the device system breaks down. You can reset the device to check whether the problem persists. If the problem persists, we cannot remotely detect and locate the fault based on the problem symptom. Therefore, you are advised to send the device to a local maintenance center for maintenance.
To obtain device firmware, contact the Consumer Platform, local device provider, or local ISP.
Thanks!