Last night in Sweden
The following happened last night in Sweden. I found and read this thread on this discussion topic and your most appreciated comments and stamina, Csound1, clintonfrombirmingham et al.
Well at home I collected the two identical internal SATA flat ribbon cables I´d ordered from a bay for the macbook pro late 2011, 13", A1278. An hour later the first cable was luckily exchanged and fully functioning direct upon start. Six months of fiddling and frustration was over. No more USB! So, having in mind that dealing with these components is a delicate issue of being careful, the sensmoral of what You and others adviced is that the first thing to do if such problems occur is the following.
Listen to clintonfrombirmingham and Csound1. Seriously.
Analyse, assume, conclude whatever you want. But then.. remember what Csound1, clintonfrombirmingham et al adviced to start with.
Identify your cable components and order two of them. The problem will probably occur again. It´s a weak spot in design. As is the wi-fi cabling for instance.
Relax until you get them.
Change them or let someone help you with that. Visit iFixit for instructions for instance. Be very very cautious with bending and fitting the new cable. The less sharp the bending is, the longer it will resist failure due to thermal and mechanical fatigue. Bending it means permanent deformation and stress concentrations. Imagine what dynamic heat loading will do. It´s almost bound to fail, sooner or later. Insulating them further from the cooling aluminum body is questionable.
Test the internal SATA function for your HDD. Hopefully you are up and running again!
If not. Don´t rule out the possibility of multiple problems, both hardware and software. They can be induced and created during the troubleshooting only by ordinary touching and pressing the components and the weak and fragile connectors.
The cost of a cable is like 10 GBP. It´s a sound approach and conclusion to start there on these most cunning problems...
Then, when you are happy again, take a look at the old flat cable, and the second new one with a magnifying glass.
You will probably see and feel the premade dents, marks and deformations across the ribbon cable where it is supposed to bend. The most obvious thing to avoid, namely mechanically damaging and deforming the thin cable wiring is there from the beginning on some cables! After high tech production. Of course it will statistically fail after some time.
I would rather have spent my time and money on perhaps buying a new component, device or peripheral instead of loosing it on troubleshooting and I hope Companies understand that this is crucial to goodwill and reputation and revenue.
The intermittent Wi-Fi problems etc. reported and discussed are many times of the same reason. The cables are very fragile and fall apart by merely pushing them when fitted even those who are not bent at all. The good thing is that the solution start is the same. Order two. Relax. Listen to Csound1, clintonfrombirmingham et al. Be gentle. Hope for the best. Continue. Best wishes.
Thanks a lot all of you helpies.