No power to SYS_5V when using 5V adapter

I do not get system power when the board is connected using the 5V
adapter. The signal VDD_5V (pin P9.5) shows 5V, but the SYS_5V signal
(pin P9.7) shows only 0.1V. This prevents the system from booting,
and no LEDs turn on (the power LED flashes when first plugged in, but
then turns off). I have also tried connecting the board via USB with
similar results. I have a revision A3 board. Any suggestions would
be greatly appreciated. Thanks.

At this point, the RMA is the right way to go.