@Tor
Silly question, but have you checked the Chip Ram SIMM? (assuming it`s the version of the A4000 that doesn`t have it soldered on..it`ll be the SIMM socket closest to the Zorro riser)..it won`t boot without any.
Also, check the jumpers match the SIMM..can`t remember what they should be set to..my A4000 manuals is in a box somewhere !
Have you tried to boot it with the Spectrum and AmigaNet cards removed??
