FAQ: Why is my Juno board hanging and/or powering down in U-Boot / EDK2 UEFI?

We've had reports of a number of Juno boards either powering down or hanging indefinitely upon entering U-Boot / EDK2 when using Linaro Release 16.03 onwards; in some cases this is due to a miscalibrated thermal sensor triggering the system control processor's thermal protection shutdown mechanism causing it to remove power from the A-class processors.

To fix this, unplug the Juno board for at least 60 minutes and enter the following command:

    Cmd> recal

Then unplug the Juno board before powering it up again; it should now successfully boot.

Note: Simply power cycling the Juno board after issuing `Cmd> recal' is not sufficient; you must physically unplug the board.