Macbook Pro does not recognize bootable USB drive I had problem with the hard drive of my 13" MacBook Pro 2009.  I decided to use the opportunity to upgrade to an SSD.  I replaced it with a 480GB SSD.

Following this article: Create a bootable installer for OS X,  I created bootable USB with El Capitan. The USB works with the computer I created it on.

On my upgraded Macbook,  normal power-on ends with grey screen with flashing folder icon, as expected - there is no OS there.

When I plug the USB drive in and hold the Option key, expected menu with choice of bootable devices does not show. There is the booting sound, the screen turns white with cursor on. The cursor responds to the touch pad but no booting menu appears. 

I don't know how to troubleshoot the issue.
The Problem is most likely that the USB Drive was not properly formated and is missing the EFI Partition. You could check via the Terminal by using 'diskutil':

diskutil list


The Result is a list of all Drives and their partions. A bootable USB Drive should have a separate partition like this:

/dev/disk11 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *16.0 GB    disk11
   1:                        EFI EFI                     209.7 MB   disk11s1
   2:                  Apple_HFS OS X 10.11 Installat... 15.7 GB    disk11s2


The easiest solution would be using a third party tool. You should try again using the Freeware 'DiskMaker X'. It formats and creates a bootable USB Drive with the OSX-Installer in a very easy and reliable manner.