Have you tried the recovery steps ?
1. Press and hold RECOVER button (SW2) |
2. Press and hold RESET button (SW1) for 1 second |
3. Release SW1 |
4. Release SW2 |
5. Re-program the board |
Also check if you have another terminal window holding the HCI COM port.
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Thank you for your reply.
Ｔhe problem is resolved 。
The reason is I did not shut down HCI COM port.