If the 2012 bottom panel is like the mid-2010, there are a couple of points in the middle where it latches on. As long as you know they are there (I think one of the OWC videos details this), it's easy and worry free to pop it loose. Also, when you put the bottom cover back on, you should press on it around the middle to secure it properly, although perhaps just turning the machine back over and setting it down will do this anyway.
thats nice to know now at least. i went and set on the couch with the macbook pro in my lap, a few seconds later.....POP. it popped back in place. scared the crap out of me again. every things still going good though.
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While I appreciate you trying to help, you are in fact spreading outdated information. With the 2012 models, there have been reports that the optical bay can, in fact, deliver SATA-III speeds. In the 15" model at least.
http://blog.macsales.com/14064-expand-the-2012-macbook-pros-with-an-owc-data-doubler
Now there are people in this thread saying that they are having problems, so we're trying to narrow down the possible reason. Drive cloning seems to be a possible culprit. However, I'm wondering if the problem steams from the OP initialing using the SSD in the HDD bay and then moving it to the optical bay? Maybe if you start with the SSD there won't be any errors? I'm not a tech wizard but I'm still going to try my new 830 in the optical bay. My caddy should arrive on Saturday...
yeah, at this point i would say the op needs to just leave everything where it is, and do a clean install on the sad (wherever it maybe) no point pulling crap apart again. I'm 99.9% sure it is the cloning that screwed everything up. Im on day 3 with my 830 installed in the optical bay...going strong.