STM32 MCU stopped working after flashing. Re-flash not possible as STM Target not found

[Nikhil_PPM]

Hi

We are using STM32H573 in our devices. 
Recently we have started to face an issue where once we flash the device the MCU stops working and when we try to connect to the cube programmer to re flash the board, the cube programmer shows no target found.

I have a feeling that the MCU is hung as I was able to find two GPIOs, one being pulled high, and the other being pulled low. 

Is there a way to get the board re flashed? I have tried making the BOOT0 pin high and connect to programmer but of no help.

Pls let me know if there is a way to debug and resolve this problem. I have 3 boards with the same issue.

Programmer: ST-Link V2

Regards,

Nikhil 

[Peter BENSCH]

Can you please upload a photo of your ST-LINK/V2, back and front?

[Tesla DeLorean]

What is your code doing?

Does it break the debug interface by interfering with PA13 or PA14? Or go into a low power mode?

Is VTarget connected to Pin 1 of the ST-LINK 20 pin header? The ground?

Is NRST connected to permit "Connect Under reset" to be workable?

With BOOT0 jumpered high can you power cycle the board?

Custom board? Provide salient portion of schematic.