To read the firmware version off of a WSD, push and hold the push-button for >10 seconds. The LED will blink rapidly from 5-10 seconds, then it will blink more rapidly once the button has been held for >10 seconds. Once you let go of the button, it will then go through the "firmware blinkback".
The firmware version of the device will show as a combination of rapid flashes and blinks (rapid flash = zero, #of blinks = #). So for a firmware version 1B, we blink two digits out the number first (1 =0,1), then two digits for the letter (B = 0,2). So 0,1,0,2 would get blinked out as rapid flash, 1 blink, rapid flash, 2 blinks, pause, repeat 2x more.