STM32 Cube Programmer detects the nucleo but won't connect

[CopperMoon]

Hi.
I’m working with a Nucleo H7A3ZI-Q. It used to work fine, but one day after we did some measurements it suddenly stopped refused to download code. I’m now trying to troubleshoot it. 

When connected to STM32cubeprogrammer, the board is detected well, but it does not connect, and gives me this error:

 

and this error in the fail.txt: The interface firmware FAILED to reset/halt the target MCU
 

I am also able to update the card with STLink Updater through STLink-V3, which I have done succesfully, but the result remains the same. I have tried on a mac and a windows.

[Andrew Neil]

Here is your problem:

 

The Target microcontroller (the STM32H7) is not powered !

Check the board’s User Manual for how to correctly configure the power options.

 

PS:

It used to work fine, but one day after we did some measurements it suddenly stopped

So did you change something to do those measurements ?

Or maybe you short-circuited something ?

Check power supplies.