Unable to detect the chip after programming

[vbk22398]

 I am programming my STM32F423RHT6. But due to some reason, suddenly I am unable to code the MCU. The connection is getting lost for some reason. I don't know what is the reason for this behavior.  I am attaching my code along with this message. The debugger which I use is an external debugger of stm32. I tried changing TCXO, tried changing the same CHIP. Voltage levels are as per the data sheet. For the 1st few times of programming, am able to flash the code. But after couple of times, facing this issue. 

Note:
I kept programming for peripheral by peripheral and this issue happened suddenly all at once. After finalizing the product and manufacturing parts and soldering, I am facing this issue. Kindly help me out.

Is my chip being dead after few instances of programming?

[AScha.3]

Set CubeProgrammer to mode: normal and reset: software or hardware (try both).

Then show, what it tells.

[vbk22398]

@AScha.3 It is giving ST-LINK Error. (DEV_TARGET_CMD_ERROR)

[AScha.3]

So no connection to st-link at all ?

Try other usb and other usb-cable...