If this problem occurs, you can try to upgrade with SD （FAT 32）card as follows:
1.Use the card reader to connect the micro SD card to the computer.
2.Download the compressed file on the computer, right-click the mouse after the download.
3. Transfer TF_ recovery.img and tf_update.img Copy the file (do not unzip) to the micro SD card, and do not put it in any folder.
4. Camera power off - > insert micro SD card - > camera power on.
5. At this time, the camera "yellow light is always on", which lasts for about 2 minutes.
6. After the upgrade is successful, the device will automatically start and reconnect.
Note: after the micro SD card is upgraded successfully, the upgrade package name in the card will also be changed to TF_ recovery.img.bak or tf_update.img.bak
Please use SD card of 32g and below
Attach the download address of the upgrade file: