File:optiPoint 400 standard migration to SIP.zip

It's possible to change back HFA image but it's not a trivial process. You need a *.fli image for HFA of Opti400 standard and Netboot and TFTP server (described on the same link). Opti400Standard sends a broadcast immediately after start-up (BOOTP) and Netboot can return a address of TFTP and a boot file name which will be downloaded.