Yours is not the first report of this I have seen here. I would try removing the card and and booting up. Use integrated or other video card. Run DDU and put your card back in see if this allows it to boot and you can then load the latest driver.
I would also report this directly to AMD as this issue seems somewhat widespread. The more people they hear from the faster it is addressed. Realize this is something the Windows update hosed not the drivers, but will likely be AMD having to fix it. Open you support ticket here: Email Form