It's a little freaky with this update.
When you load the update, the camera with flash "Loading" and if you miss the "complete" and the blinking SD card light by a second, the camera will just go blank.
In the past, the update would "blink complete" for as long as it took until you turned off the camera.
I put my one K3 down, and looked away and did something, and almost freaked because it was just a black screen when I came back.
Good thing I had another K3 where I actually watched the process.
So don't freak if you miss the "complete".