extend XBT's explanation
The final approval notice from USCIS based on NO objection application is also shown as I-612 approval notice. That is the final notice you have obtained from USCIS.
However, for NO objection application, it needs to apply through DOS directly but not USCIS. As XBT explained before, only application through hardship or other excuses will need to submit an I-612 application to USCIS directly.