Error message on screen at boot: any hints?

[aotta]

I got my first FM-TOWNS II, i knew it was not working but i'd like to understand what is wrong and if it could be fixed.
At power-on, after few seconds i got an error message on screen, that i translated in something like "system error, press reset!":

some time the screen has some garbage, but same message:

I tried to boot from cd, bluescsi2, floppy, but it seems that the FM-TOWNS don't even try to boot.
I already changed the battery, i wonder if it's the SRAM (IC18) or the PROM (IC22) that are faulty and stop the boot routine. I already ordered a new SRAM, while the PROM MB8541p i'm afraid it's not replaceable (it has a label with "03" upon, is public the code programmed in the PROM?)

Any suggestion?
Are schematics available (i didn't find them)?
Thank in advance