If you have access to the "ACI-N9KDK9-12.2A" image you want to boot from, the process for converting to ACI mode is pretty well outlined in this document: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/upgrade/guide/b_Cisc...

Howdy knothukuri,   To start, here is the documentation on carrying out a cold upgrade of a VPC: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/nx-os/tech_note/vpc_upgrade.html#pgfId-51350   Answering each of your questions directly: "D...