BeagleBoard-xM won't boot

We had purchased a BeagleBoard-xM (rev B), and were able to deploy it
successfully for our application. However, we have recently
encountered a problem, the symptoms of the issue being:

1. Upon supplying power to the board using the recommended 5V @ 3A DC
adapter, the D6 LED of the microSD slot does not turn on, and the D7
LED only glows faintly.
2. The board refuses to boot up, regardless of which microSD card we
use (we have three compatible microSD cards, all with OSs loaded, and
they all used to work earlier).

Any thoughts what the issue might be?