Chosen Solution
boot manager not showing both ssd drive and bootable pendrive. i was previously having 128GB SSD, bought a new SSD (500GB) and fixed into the Macbook pro. i also made a bootable USB to reinstall my OS X Yosemite when i power the Macbook and i press the the option key i only get to see the Recovery Disk, i can’t see both the bootable pendrive and the SSD in the startup manager. The interestion part is when i boot into the recovery and access the disk utility there, i see all drives… i have formatted the drives there but still. kindly help me out with a possible fix. thanks.
I suspect the USB drives was not reformatted so its still using FAT32 or exFAT and your Mac won’t boot from that kind of format it needs GUID. Go back into Disk Utility and compare your formats between the drives.
