Hi- are you able to test the USB board on its own with another USB cable, maybe on another computer? You should have a new com/serial port show up in the Arduino IDE(or another program) as you would expect from the FTDI chip. If not, shoot an email to info@tiny-circuits.com
The LED is not a power on LED, it's a general purpose LED(the usual pin 13 LED)- sometimes the bootloader toggles it depending on the internal state, so it's not necessarily indicative of a fault with the processor if it doesn't flash.
Thanks,
Ben