Fixed now! I got impatient and got it working using the bricking/interruption method explained here:
Another important note that may help people frustrated with the WF4720 Firmware Update mode. None of the pressing positions worked for me and I searched all over the web. Almost gave up...then it worked.
This was my exact setup:
1. Turn printer off. Still plugged into power.
2. Connect to your computer with cable >>> USB Type A male cable with the printer Type B male on the other end.
3. The button presses... only this worked for me:
>>>> First put your thumb print (not just tip, more flat and horizontal) in the top right part of the black glass...not the display box inside...outside that on the glass's top right area.
Start pressing this first.
>>>> Quickly press and hold the power button...keep on holding. If you're doing it right there won't be a blue light for 20 seconds and screen will be dark.
>>> As soon as the blue light goes on, release! And boom!
I saw this 20s technique for other models on YouTube, but everything for the WF4720 said 3 seconds and all the variations on this just turned on the printer.
Glad I played around with it. This is a store-bought Canadian model.
Good luck all! Thanks for your service chipless. Damn ink robbery with those companies.