TM4C1290NCPDT: Locked MCU -- program looks for external clock. how to recover?

Hi all

I have a custom board with a TM4C1290NCPDT microcontroller. After loading my second program (the LED blinking worked) I tried to load a UART testing program, which required me to set the system clock. Though the board does not have an external oscillator, I set the code as follows:

  //
  // Set the clocking to run directly from the crystal at 120MHz.
  //
  g_ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
					   SYSCTL_OSC_MAIN |
					   SYSCTL_USE_PLL |
					   SYSCTL_CFG_VCO_480), 120000000);

Since that time the board no longer appears to JTAG ("failed to connect") and I'm assuming that the clock setting above is to blame.

I've tried the LMU programmer erase via an ICDI launchpad (TM4C123GXL eval board) with out luck.

Any suggestions on how to recover the board?

Thanks

Peter

However, the board does not have an external oscillator (oops) and now I can no longer load the board