According to the internet this is a known issue. The "solution" appears to be that you take it to the Apple Store, ppay $300 or $500 and have one of three outcomes:
1) It solves the problem
2) It solves the problem for X months
3) It still doesn't work and they try something else
While I did want t code this weekend, I have other stuff I can do. So while it would be inconvenient not to have my primary computer this weekend, I could still get most things done.
I'm also looking at whether it is worth having them fix it or just to get a new computer. I'm thinking to have them fix it and then order a new computer in a month. (March is busy; I don't really want to be setting up a new computer now.) It looks like the current choice is a 15" Mac Book Pro Retina, right? (I have a 17" now). Anything I should know?
This happened to my 17" as well a year or so back. I eventually brought it to the Apple Store and it got fixed under a "first-time out of warranty" program for some ridiculously small sum considering they replaced the logic board, the display, and the battery.
But, I needed a new system anyways for my previous contract so I purchased the top-of-the-line MacBook Pro retina. I'd recommend getting the SSD and getting it maxed out with memory. Not cheap, but those two items made a world of difference.
The Apple store has my computer. They are fixing it for free. (List price including labor for this repair would have been $529.) Since this fix is free, no need to consider whether to buy a new computer at this time.
This is the second time I've left my computer with the Apple store to fix something. Both times they asked for my user id and password. When challenged, they said they didn't need it. Then why the *&^*! do you ask for it. It's poor information hygiene to give out your password. A reputable business shouldn't be asking.
And neither time would being able to login help. Last time was for a battery change. This time, it is for a problem that happens as soon as you turn on the computer.