A couple of revelations:
1) The SBC board only seems to work with 512kb E(E)PROMs.
2) The first EEPROM I used turned out to be "One Time Programmable"
3) When putting the POST card in one of the ISA slots with the indicated side facing the PC back side smoke arose from one of the components (pulled the plug right away)
4) Using a 512kb Eprom I did manage to flash the Patch2 file onto it. The system works fine with Patch2 but the problem of not booting from C drive remains.
5) Attached the screenshot with the output from the Debug command line.
It´s funny, when using a bootlable disk I can without problems access the c drive and install software on it. Thus, I´ve installed Adlib and Mouse drivers and installed Monkey Island without a problem. Just don´t get it why it won´t boot from the C drive.
Hope we are getting close to the solution of the problem. Thanks again for your invaluable input.