I think my MacBook Pro is badly, badly bricked. Model is a1286
It's a really weird story.
This MacBook Pro had 2 partitions, one with Lion and the other was Windows but not accessible becouse was corrupted (if you tried to boot this partition, it would just show black screen and nothing happened).
BTW Lion was slow so I made a bootable USB and entered the recovery to do a fresh install of a new High Sierra system and I just erased the content of the Macintosh partition (the one targed Bootcamp was locked and didn't allowed me to erase).
It was ready to install a new system, but the bootable USB I made with High Sierra was not seen in the boot menu, that I entered pressing alt when powering on.
So I read in a forum that doing NVRAM reset could help, so I did, but the result was terrible.
Black screen and can't access to recovery or boot menu anymore.
I tried everything. I've also opened, and tried disconnecting the battery and the RAM and reconnecting them to see if changed something but nothing. Or powering up without the battery only with the power supply. Also tried to replace the HDD with another one formatted in HFS+ but nothing.
Now it just shows a black screen and does not recognize the commands.
If it can matter, the sound card is faulty and I used it with a USB one.
Recovery pressing command + R
Recovery pressing alt + command + R
Boot menu pressing alt
Nvram reset pressing alt + command + p + r
SMC reset pressing shift + Alt + ctrl + power for 10/12 sec
The light of the USB bootable drive is always flickering when connected, but doesn't show nothing on screen.
Did I just destroy it?