Are you using supervisor modules for the C9400 as edge?
Are ISIS adjacencies formed in VLAN 1 before stopping the LAN automation process? you can check with "show isis neighbors" on the Borders
In which step of the LAN automation process are you stuck?
- C9400 links are up after booting up?
- C9400 gets IP via DHCP from borders?
- C9400 can reach DNAC to start the PNP onboard process?
- Borders and Edges are ISIS neighbors in VLAN1 before stopping LAN auto?
Regards