If the LEDs are solid, and you don't see any output from the UART, most likely the module it toasted.
The link LED (yellow) should blink 3 times when the ME is powered up (assuming that the network cable is already plugged in).
After that, the device should end the boot and then the LED (yellow) should come on solid.
This is assuming that the network connection is good.
The activity LED (green) is blinking during the network transfers only (however it can be on for long periods sometimes).