MacbookPro bootable Windows USB not visible I have a MacBookPro retina (id MacBookPro10,1 mid 2012) with El Capitan installed and want to create a Windows partition through BootCamp. I already did that some time ago without that much trouble, but had to wipe out the entire harddrive and install both systems from scratch.
This time I did:


By "hacking" BootCamp made it install Windows 7 boot into a USB I have.
Downloaded and copied over BootCamp drivers for windows into this bootable stick.
Disabled FileVault, that prevented external devices (even recovery HD) from being seen on boot.
Turned off System Integrity Protection (had to do that already to make step 1 happen) with csrutil disable in recovery.


The problem I am having now is that the USB is not visible on (hold option key) boot even if it is plugged in and is lighting up. I tried installing reFit, but it also does not see the USB. Not only that, the interesting thing is that this USB is not even visible in reFit partition table you can see in the options.

UPD: another interesting thing, the USB is not visible in startup disk setting inside OSX, this may mean that for some reason even if the USB drive itself is visible, Mac does not recognize it as bootable. Or is it because startup disk is not able to see USBs at all?

How can I troubleshoot this on El Capitan?
I managed to install Windows 8 on the system, and would like to post my findings, since I am sure others will run into the same issues I faced.


The problem reported in this post had to do with the windows iso images themselves, not with Bootcamp or EFI. To make sure your system will even see the USB at all, make sure it has the file /efi/boot/bootx64.efi otherwise Mac will not even see the usb as a bootable device.
To anyone speaking Russian, this link will be very informative on how the entire process works http://geektimes.ru/post/213223/.
If you are installing Windows 8 (I would still like to know if anyone managed to install Windows 7) make sure you do everything through BootCamp, especially partitioning, since the first time I tried editing the partitions manually, I managed to screw up my recovery partition (repaired by downloading and installing El Capitan again without data loss). Not only that, I managed to stop seeing 'could not set up bootable device' errors only when I went through all three steps in Bootcamp on a single session. What I really dislike is that downloading fairly large amount of drivers during step 2 of BootCamp fails if there is a network problem, and I had to restart the entire process a lot of times.
I ran first aid on recovery partition as shown in this post: 
Problem Installing Boot Camp Windows Partition on new Mac Pro
but judging from documentation of El Capitan this should not be necessary since the OS should repair write permissions automatically, therefore I am not sure whether the method shown here is necessary any longer. I did not reset my PRAM.
During the last part of Windows installation, the one after you create the user account and wait, the computer froze. However, after hard reset the system started normally and I could make the last step of installing BootCamp drivers from the USB.


To sum it up, make sure the Windows image is x64 and bootable by EFI and make sure to carry out USB creation, driver installation and partitioning of the system by BootCamp only and in a single clean swipe.