boot failure diagnostics

[Vwaju <lou@manhattanhandyman.com>]

Out of the blue, Debian failed to boot.

Using debian-live-500-i386-rescue.iso I mounted the root partition /
dev/hda1.

I would like to examine the partition to find the reason for the
failure.

I'm guessing I should use fsck.  Is this right?

However, I don't know what options to give it or *what I'm looking
for*.

The man page is kind of sketchy, and I don't feel encouraged by the
following:

%fsck /dev/hda1
fsck 1.41.3 (12-Oct-2008)
e2fsck 1.41.3 (12-Oct-2008)
/dev/hda1 is mounted.

WARNING!!!  Running e2fsck on a mounted file system may cause
SEVERE file system damage.

Do you really want to continue (y/n)?

As always, I'm grateful for any guidance you can give.

Best Regards,

Vwaju
New York City