MacOS – Left shift and alt are stuck together

If the product you used to clean the keyboard was wet, you could have created a short in the keyboard or perhaps even corroded the contacts under the Control key.

Two outcomes:

1. You give it a few days to dry out.
2. You buy a new keyboard.

Hopefully #1 will take care of it for you!

In the past, I've scrubbed nasty, dirty keyboards with a firm brush and water under a bathtub faucet and then let the keyboard dry out for a week. However, that was not the low-profile "laptop like" keyboard that Apple has been providing for the last decade, so I can't say that I've done it on modern Mac keyboards. But that all being said, the key thing is that clean water (NO SOAP!) should leave no residue (unless your water is very hard) and as long as you don't introduce electricity into the mix while it is still wet, you shouldn't be risking creating permanent short circuit damage.

http://www.apple.com/support/macbookpro-videoissues/

Apple has issued a Repair Extension Program for Video Issues. I was experiencing the same problem and had tired several solutions that worked for a short period of time, but ultimately I was unable to get my MBP up and running last night and brought it into an Apple store. They determined that my issues was in fact a video issue and qualified for free service.

If you purchased a MBP between February 2011 and December 2013 and suspect that your MBP is experiencing the same issue, then check out the page URL above to see if your MBP qualifies for service.

Here's an excerpt from the page

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Apple has determined that a small percentage of MacBook Pro systems may exhibit distorted video, no video, or unexpected system restarts. These MacBook Pro systems were sold between February 2011 and December 2013.

Apple or an Apple Authorized Service Provider will repair affected MacBook Pro systems, free of charge. See below for details on affected models and service options.

Symptoms

An affected MacBook Pro may display one or more of the following symptoms:

Distorted or scrambled video on the computer screen No video on the computer screen (or external display) even though the computer is on Computer restarts unexpectedly

Products affected 15-inch and 17-inch MacBook Pro models manufactured in 2011 15-inch MacBook Pro with Retina models manufactured from Mid 2012 to Early 2013