Lpc2000

We developed a prototype board with an LPC 2138 and JTAG interface. It
worked initially as I was able to program it using the IAR and JLINK.
After several reprogramming steps, the chip isn't responding anymore.
I see activity on output ports that are used by my application this
indicates the core seems to be fine. When I try to debug the
application in IAR, I get the error message: Received 0 as core Id. No
communication with core. I get the same error message using Segger
comandline tools. The chip doesn't respond to ISP commands. Is there
any way to erase the Flash completely?