Ran into this issue today and wanted to share how I fixed it as there is not a lot a lot of info online on this issue.
We upgraded our NetApp controllers to Ontap 9 and reboot all our iSCSI attached LDOMs after. One of the LDOM did not come up cleanly and it would not accept any keyboard inputs at the console. Even in single usermode. After searching a lot online, I found that this is actually a bug. Bug ID: 19388985.
The fix was to power cycle the host. a reboot will not work. You will actually need to shutdown and power on the server.
- shutdown server: init 0
- from ILOM: start /SYS
Hope this helps some one.