I have a number of boards with the LPC43S57 with SPIFI flash. I can program this using my Segger J-Link debugger. For a test I needed to program the internal flash, but when I tried that I got an error, and from that moment on I could not access the processor anymore using SWD (or JTAG). I tried programming the image in a second board, but there the same happened. So both boards are effectively dead now, as I cannot access them anymore and no valid application is running.
When I try to connect using J-Flash it says that it cannot connect to the target.
What could cause the processor to stop communicating over JTAG? How would it be possible to break the JTAG by just uploading an image into the internal flash? Is it possible to bring these targets back to life?