Plan B... I'll use my iPad. I opened it, and the start-up screen with the Apple on it appears... and doesn't disappear. Another time it started blinking. I Googled "my iPad opens with the start-up screen but doesn't do anything." I tried some of the fixes I found online and was able to get it up and running a few times, but it kept coming back to the Apple, despite my fixes and my updating software.
I Googled "my MAC book space bar doesn't always work" to see if there was a recommended "fix". (What would I do without Google?!) It turnes out that to keep the slim profile of the MAC machines, a different "spring" was developed to create the same feel as a regular keyboard. This "Butterly" spring has developed a high rate of failure. Ah hah! It wasn't necessarily crumbs impeding the movement.
So, I made an appointment at the closest Apple Store Genious Bar... for my laptop AND my iPad.
The iPad turned out to be a bit more problematic than the MAC book. The technician plugged it into his computer so that it could run diagnostics. It didn't work. He pulled out a different cord, and tried again. It didn't work. He found another computer, and tried again. It didn't work. He borrowed another cord from a coworker... ta daaaaa! It finally ran the diagnostics. However, despite the diagnostics apparently finding the problem, the iPad would not progress past the Apple start-up screen. As my iPad was still under extended warranty (I am so glad that I bought Apple Care) I was given a new, refurbished unit.
Next, the technician tackled my laptop issue. He tried the keys and agreed they did not work correctly. He took the unit into the back to open it up and have a look. When he returned, I asked if the problem I was experiencing was due to the mice. He looked at me with a quizzical expression. I pointed out that with the amount of crumbs that were probably under the keys, there must be a family of mice in there as well. He laughed, and assured me that there were no mice, probably because the snake that had moved in had taken care of the mouse population!
I had to leave my laptop at the store. I received a notification the next morning that it was ready for pick-up. I am now typing on my repaired laptop which has remarkably springy keys and a spacebar that works! Hallelujah!