EK-TM4C1294XL: Target device failing to communicate with debugger

Hello,

I'm using the TIVA Connected LaunchPad as a development platform for an EVM. We've used these extensively in the past. Recently, I've managed to cause a number of the target devices to fail while running the debugger in CCS and they cannot be recovered.

A few details that may provide some clarity:

1. I've replaced the target MCU on two of my LaunchPads with unopened devices from a previous EVM build. When the program reached main(), the debugger "lost connection with the target." After that point, I was never able to communicate with the target again.
2. In this failed state, the debugger MCU no longer enumerates in Device Manager. However, I've found that I can hold down the RESET switch on the target side, and Device Manager will update to show the Virtual Serial Port, the ICDI DFU device, and the ICDI JTAG/SWD interface. Upon releasing the RESET button, all three Stellaris devices disappear from Device Manager.
3. "MCU_3V3" still measures 3.28 V.
4. Target seems to draw about 17.1 mA without pressing RESET. Holding RESET reduces the current draw to about 5.6 mA.
5. JP1 = ICDI. JP2 and JP3 installed. JP4 and JP5 setup for UART.

Thanks and regards,