u/seregaxvm

Hello! I've followed installation steps for OnePlus giulia CPH2691 and got stuck on the sideload step. The device shows the following error message:

Installing update...
Error: recovery: Open failed: /metadata/ota: No such file or directory
Step 1/2
Error applying update: 7 (ErrorCode::kInstallDeviceOpenError)
ERROR: recovery: Error in /sideload/package.zip (status 7)
Install completed with status 1.
Installation aborted.

Now I only have access to fastboot and recovery mode. There's root access to the device via ADB. Is there a way to make sideload ignore this error as due to rollback prevention, I cannot flash original ROM.