update firmware

Hello RUBENSCOSTA,

Thanks for that info and choosing the Apple Support Communities. I know how important getting your Cinema Displays working again is to you!

If I understand correctly, you are unable to update the firmware on the LED Cinema displays. I would try these steps to get these working again:

1. Make sure your iMac has all available firmware updates installed as well:

About EFI and SMC firmware updates for Intel-based Mac computers

2. Try following the process in this article on LED Cinema Display updating:

About the 27-inch LED Cinema Display Software Update 1.0

3. If you're still having issues, you may want to review this general troubleshooting guide:

Get help with your Apple Cinema Display

Cheers!

Thanks for that additional info, it really helps! Since these are Thunderbolt Displays, try running the update in Safe Mode:

Try safe mode if your Mac doesn't finish starting up
Limited graphics performance in OS X recovery or safe mode

Then restart your Mac and use this article to see if the update was applied successfully:

About Thunderbolt Display Firmware Update 1.2

Cheers and have a great day!

Thanks for trying that and taking screenshots. Let's perform the steps on this Apple knowledge base article next:

Thunderbolt Firmware Update 1.2: Keeps reappearing and Thunderbolt ports and Target Display Mode may not work

Cheers and have a great day!