Hi @P007,
Are you able to connect to target without uploading an image?

If so, please try and stop the MCU to see if it is stuck somewhere in application.
Also, you could try to reset or erase the chip from the JLink flash tool (e.g. JFlash.exe or JFlashLite.exe, you can find it in the installation directory of Segger J-Link).
If these still do not work, please try another MCU or debug probe to see if the issue is within the hardware.
Best regards,
Julián