OCLP + macOS Sequoia on iMac 5K (Late 2015) — Password suddenly rejected after power outage, can’t reset password, no Terminal in Recovery, USB installer won’t boot (-5101F, -2003F)

Hi, I really need help.

I updated my iMac 5K (Late 2015) to macOS Sequoia using OCLP.

After a power outage today, the Mac rebooted and suddenly refused to accept my login password — even though the password is definitely correct.

I’m not a native English speaker (I’m Japanese), so sorry if my English is a little strange.

Here is everything I’ve tried:

1. Command + R Recovery

   • It does boot into Recovery.

   • But Password Reset Assistant fails every time.

   • No matter what volume I choose, it gives an error and does not continue.

   • Terminal does NOT appear in this Recovery environment.

2. Internet Recovery

   • Using wired Ethernet.

   • Always ends with -5101F (and earlier I also got -2003F).

   • Seems unable to connect to Apple servers.

3. USB Installer (OCLP-created macOS Sequoia USB)

   • Startup Manager shows the USB, but:

   • selecting it freezes, or

   • it returns to the login screen.

4. SD card boot

   • Same behavior — freezes or goes back to login.

5. Suspected cause

I think the power outage corrupted:

• my user account, • login bundle, • or something in the file system related to authentication. 

Now I cannot log in AND cannot reset the password.

My questions

Am I completely stuck?

Is there any way to:

• force Terminal to show up in Recovery, • bypass or repair the broken password authentication, • rebuild the account files, • or reinstall macOS without losing data? 

Any advice would be massively appreciated.

Right now the machine feels totally bricked.

Thank you.