I've got an RB5009 in my lab and it certainly seems dead. Woobm on USB port shows nothing via telnet or Web UI. I plugged the power in while holding down the reset button for 30 seconds waiting for blinking but nothing happened. Anything else I can try?

Check power supply.
See if you can use another one with the required range for RB5009 (24V-57V).
You can also try PoE In as power source.