Black screen, CMD-R not working

[Henri9009]

Hi all!

I did a stupid mistake: I renamed the HD and now the system can't find it.

I was setting up my girlfriend's new MacBook 2015, and at the end, I couldn't use Time Machine because the data HD and the main HD were named the same: Macintosh Data.

So I renamed the main HD and Time Machine was working.

Now all I have is a black screen, but what I don't understand is that CMD-R at the startup is not doing any effect (I do it right after I press the start button, and I hear the Apple startup sound all right). Nothing happens, I just see all the time the black screen.

Thanks for you help!

 

[Fishrrman]

I don't see how just "renaming" a drive could do that.

Something else is going on.

If you plug in the charger, does that change anything?

 

[Henri9009]

Sorry about that useless message!

Precisely at the same time, it seems I'm experiencing a screen problem, so I thought it was related (to the HD name change).

 

[DeltaMac]

Be sure to try an NVRAM reset- hold Option-Command-P-R immediately after you press and release the power button.
You should see some kind of video flashing, but on a 2015, you will hear the usual Mac boot chime sound. Keep holding the same 4 keys until you hear the boot chime two more times, then, while you can still hear the boot chime, release the keys, continuing to hold the Option/Alt only.
(What do you get on the screen for choices when you boot holding the Option/Alt key?)

I think the best way to move ahead:
If your girlfriend likes a different drive name, boot to an external installer for the macOS version you want to use.
Launch Disk Utility, change the View menu to Show All Devices.
Select the top item, which will have the manufacturer's info. Erase THAT. You can choose to format as APFS, or you could erase using Mac OS Extended (journaled). It makes no difference at this point, because any system installer after High Sierra will change the drive format to APFS automatically.
Notice that you can enter a new name for the drive in the Erase window. So, whatever your girlfriend likes for a drive name.
DON'T try setting up the various drive names, or anything with - Data added to name... The macOS installer will handle all that for you during the install, and you will end up with all the correct volumes (with correct naming) that you need to allow use of the MacBook.

And, now that you have a drive with the chosen name - reinstall a fresh version of the system that you want to use.
If you actually have a 2015 MacBook (and not a MacBook Air, or MacBook Pro) you are limited to Big Sur. A 2015 MBPro, or Air can go to Monterey.
Finally, if all you get is a dark screen in all this, the MacBook needs repairs.
"New" 2015 MacBook? Take it/Ship it back to the seller.