I have both a 9,1 and a 9,2 Mid-2012 13" MacBook Pros which have both failed. Having finally gotten both computers back from my daughter, the only thing that I can find wrong with either one is that it appears that one of the two memory slots has failed in each computer. (Mr Google has led me to places that have the story that Apple put a little too much torque on the screws holding the ports to the motherboard. And also the news that the only way to fix this is to replace the motherboard.
I bought a refurbished 9,1 last summer which came with a single 8GB SODIMM in one slot rather than the advertised 2x2GB. I sent it back when I realized that it had a failed RAM slot. So apparently this is not an uncommon failure.)
These machines were long-ago upgraded to 16gb by replacing the original memory with a kit of 2 8GB SODIMMs, and so taking one out leaves me at 8GB, which is a sad place to be. When I go to Amazon and look at the product for 2gb, 4gb & 8gb Crucial chips, there is also an option for a single 16gb chip or a 2x16GB 32GB kit that's on the same form factor.
So now I'm wondering if I can get one of those 16GB chips for each computer, put it in the working slot, and have 16GB. According to this Macrumors thread, the answer is "no"
The important point is that while Ivy Bridge does support 32 GB, it only supports 8 GB per module. You'd need four slots for 32 GB to work, and the MacBook Pro (like every other laptop pretty much) only has two.
But I can't figure out if this is really true -- this post here gives me some hope although it shows a screen shot of Crucial saying "no".
Does anyone know anyone who has tried this and know one way or another?