I had a problem similar to this.  If you aren't getting "death chimes"
(i.e. a minor chord) when you turn it on, you probably have a software
problem, not a hardware problem.  In my case, it required a system clean
install* to fix it.  You can also try attacking the disk with Norton or
something like Disk First Aid or HD setup.  For me, only the clean install
worked.

You may be asking, how can I install to a disk I can't mount?  Well, I
found that even though I could not boot from the drive, it would mount if I
booted from another disk.

Good luck,

--Rob.

* A clean install is when you drag the current finder and system to the
trash, rename the system folder, and then install the system.  This forces
the installer to build the system from scratch.  Alternatively, you can use
Cmd-Shift-K in the System 7.5 installer to force it to perform the clean
install.

At 9:02 PM 2/7/95, Yulim Tan wrote:
>This time, it's not a joke! Today afternoon, I ended a unix's work
>session and shut down the machine (Mac IIci) with the command:
>shutdown now, as usually.
>when the hard disk stopped to work and the prompt appeared again, I
>switched off the mac. But half an hour later, when I wanted to use it
>with macOS again, the sad mad appeared when it started to read the
>hard disk, with the message "0000 000A"   !!!!
>                            "0000 000F"
>
>My computer doesn't want to boot again. HELPPPPPPP!!! what happened?
>How can I get back the system? Is there someone who met the same pb?
>
>                                Snoopy