Unpack sp59543.exe and open 01646.fd (or 01647.fd) with Phoenixtool 2.14. You'll see 01646.fd.DEC (decrypted) bios and RSA.SIG file
Make a dos bootable pen drive, extract the contents of the archive in it, boot from it, at the dos prompt type 'nbdmifit' (w/o quotes).