Hi Li,
I suppose, that you use one of the small reference designs like RD9Z1-638-12V and not KIT9Z1J638EVM evaluation board. Correct?
Please specify which board you use.
According to your description, it looks like some issue with BDM connection.
Please check BDM connector orientation on both sides (at the board and in BDM multilink).
The MCU must be powered from some voltage source during programming. The Multilink debugger does not provide a power supply for MCU.
If you use KIT9Z1J638EVM evaluation board, please check DIP switch configuration for onboard/external BDM interface.
I hope it helps you.
Have a great day,
Radek
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