Can't connect to NRF52840-DK after connecting external power supply.

[BasdBerg]

I can't connect to my nRF528540-DK anymore after I connected an external power supply and switched SW10 to off.
the external power supply is 5V. my DK doesn't show up in device manager and led5 is turned off.

how can i repair this?

[awneil]

BasdBerg said:

I connected an external power supply and switched SW10 to off

Where, exactly, did you connect this "external power supply"?

Are you sure that it really is 5.0V ?

If you remove the external power supply, and put the switch back as it was, does it work as before ... ?

[BasdBerg]

I've connected the external supply to P21. The VDD line is 0V at the moment. it’s really 5.0 volt. I’ve read that the voltage level must be 1.7 - 3.6 V, so I think I blow up something.

 

[BasdBerg]

i've removed the external power supply and put everything back as it was, but it doesn't work.

[awneil]

BasdBerg said:

I’ve read that the voltage level must be 1.7 - 3.6 V

Yes, that is what the User Guide says:

Always good to pay attention to the User Guide!

BasdBerg said:

I think I blow up something

Probably.

You'd have to get the schematics out, and trace through to see if it might be fixable - probably best to just put it down to experience, and get a new DK, I'm afraid.