iMac can’t find startup disk

I recently made this: https://www.reddit.com/r/OpenCoreLegacyPatcher/s/Va0cHRwMPo

During the process, I found in the installation logs a message saying that the disk format didn't allow installation (it was in APFS), so I formatted it and set it to Mac OS extended format.

However, upon rebooting, it seems to have entered some sort of inconsistent state. I believe it can no longer find the startup disk, as it keeps restarting, showing only the Apple logo without the loading bar.

I tried resetting the PRAM with the "option+cmd+p+r" keys, and it worked, but once finished, it continued to restart (I know it worked because I hear the startup sound now).

When I hold down the option key, I don't find any devices except for the USB, which is recognized when inserted, but clicking it yields the same result.

Pressing "cmd + r" or "cmd + option + r" or "shift+ cmd + option + r" sometimes shows a folder with a question mark, and sometimes I see a circle with a line through it (forbidden icon) and then continue to rebooting in loop.

I don't know what to do, is the only solution really to take it to a repair center?

Hope you can help me. Thank you.

Author: @AdEither3244