I had a new Latitude E7480 laptop hang during a TPM firmware update today. I have updated several other laptops with the same USB drive created for the process. The update hung at the point where there was text on the screen that the TPM update was in progress and to not power off the computer. The progress meter never advanced past zero percent. I could not warm boot the laptop nor power off the laptop by holding the power button down. After several hours the laptop is still hung at that point. Any suggestions?