nrf52840dk not working, always Blinking LED5 and no appearance as JLINK on PC

[AndrewAWG]

LED5 is blinking very fast. no appearance on computer at all. nrfjprog --recover not reconvering, 
Tried another PC, another cable and no response at all. 

[Hung Bui]

Hi again, 

You mentioned LED5 blinking ? Could you take a higher solution photo of the board ? I want to check if the VEXT->nRF switch is set to OFF. 
Could you try to move the SW9 switch (LiPo VDD USB power source) a little bit, sometimes it's the contact on this switch causing the problem. 
If you have tried different cable and PCs, not much left we can do. The board may have been damaged.