Boot menu not working So basically I can't boot from my ssd anymore. It just shows a grey screen with an error symbol. I can't get into target disk mode and none of the other boot shortcuts seem to be working either.
When I have my old OSX HDD in there and the SSD attached via USB however I can select the SSD from the boot menu and boot it just fine.

Also, booting from the HDD works just fine. I was under the impression that the boot menu wasn't tied to a disk but supplied by efi or whatever. But given the current behavior that doesn't seem to be the case?!

Any ideas what my cause this and solutions are greatly appreciated!

UPDATE:
I wiped the SSD and used carbon copy cloner to clone my working HDD onto it, but it still won't get anything besides a blank grey screen with the occasional failure sign...
Your black screen, power light on steady, no chime: indicates the

POST / BootROM failure!


  BootROM
  
  When you turn on the power to a Mac, it activates the BootROM
  firmware. BootROM, which is part of the computer’s hardware, has two
  primary responsibilities: 
  
  It initializes system hardware and it selects an operating system to
  run. 
  
  Two BootROM components carry out these functions:
  
  Power-On Self Test (POST) initializes some hardware interfaces and
  verifies that sufficient memory is available and in a good state.
  
  Extensible Firmware Interface (EFI) does basic hardware
  initialization and selects which operating system to use.


I would suggest you update your EFI from here: