If the system boots and falls into “loader>” prompt. Do the following steps.
Step 1: Issue the command dir to check the directory and enter the command:
boot nxos.9.2.1.bin 
Step 2: Once the switch is booted up, set a password for Nexus 9K,
Step 3: Login to the switch.
How to prevent Nexus 9K from dropping into “loader >” prompt
As soon as you set up your Cisco Nexus 9000 (following setup of POAP interface), you need to configure the boot image in your system to avoid dropping to the “loader >” prompt after reload/shut down.