Imac can't boot with any possible ways

[Aparatus]

Hello. Please, somebody, help me with this situation. I'm really fked up, seriously.
IMac 27' Late 2011, SSD installed instead cd rom. High Sierra was (in fact - it is on ssd still).
Few days ago i met this problem. I can't boot my mac in simple mode, in safe mode, in verbose mode. I did Options+alt+R+P and then, tried again all that way. All i got - he started loading and right before the end (sometimes in the middle) - grey screen. Diagnostic "D"-command doesnt show any problems.
I have these partitions for loading: EFI - that partition appear after games with boot camp, after install - i met sound problem in windows, so i deleted. This partition always loading and it's broken, cause windows doesn't exist any longer. Next, my ssd partition with macos, which loading grey screen.
I've made BDU flash disk, and all options or grey screen, or just "apple logo" and do nothing at all.
Please, give me some advice, what shall i do? Any links, or answers will be appreciate, thanks.

 

[Cory Cooper]

Hello and welcome.

Part of the issue may be deleting the EFI partition, as it holds information about which operating systems your Mac can startup from. Also, I assume when you mentioned BDU flash drive, that it is BootDiskUtility, which uses the Clover EFI bootloader? I have no experience with utilities of that sort, as I have seen them cause more issues than they are worth. It also could be that High Sierra is corrupted.

Maybe some screen shots/photos would help us diagnose...maybe diskutil list in Terminal, Option-boot screen, etc.

This may be a bit tricky to diagnose over the Internet, but we'll try.

C

 

[Aparatus]

Hello and welcome.

Part of the issue may be deleting the EFI partition, as it holds information about which operating systems your Mac can startup from. Also, I assume when you mentioned BDU flash drive, that it is BootDiskUtility, which uses the Clover EFI bootloader? I have no experience with utilities of that sort, as I have seen them cause more issues than they are worth. It also could be that High Sierra is corrupted.

Maybe some screen shots/photos would help us diagnose...maybe diskutil list in Terminal, Option-boot screen, etc.

This may be a bit tricky to diagnose over the Internet, but we'll try.

C

Hi.
If you can tell, what actually shall i do to delete that partition - it will be awesome. I can still boot only in "Options + S" mode, where i still can type some commands, but im not so familiar with macOS so close, i'm sorry. BDU flash does nothing - still grey screen, like every mode i've tried. Please, tell me, what information you need? Photo in this situation will not help i think, if you want, i can make some video with my attempts to boot os.