🚀 go-pugleaf

Hi, I have an old (currently well used by a relative) Olivetti m300-10
(bumped up to a 486, I think) which has suddenly started hanging at
Fixed Disk startup.  When you turn the pc on, it beeps 4 times, then
hangs at Fixed Disk,then quickly flashes Disk Controller Failure 1782.
Then it goes into built in setup mode, starting with 1 USA, etc. I
choose 1, then get the HDU/F3 menu, I hit F3 and it asks for 2 HDU
settings (why 2?), neither of which I know, since the original owner
of the machine never printed out the specs sheet. I've tried entering
random numbers by hitting the space bar, ex. 34-040 mb, and putting
the same number in the second setting. I then hit enter twice, and the
system reboots to:

Fixed Disk 1782       disk controller failure 
Floppy Disk           1 present
Sys. Config. error    run setup
Primary Boot Strap
Non system disk or disk error
Replace disk and strike key    (the drive light goes on when you do
this, so the floppy is ok)

I'm wondering if it's the battery that's causing the HD to hang/losing
the settings, and what I can do about it. And/or, if it's just the
wrong settings that I'm entering, how would I ever get the right ones
in there? (There are probably 250 permutations/combos of numbers to
enter at the F3 prompt). I have the 2 disks that came with the
machine, but they only bring me to the same place that I get to when I
start the machine up anyway. The manual I have is for the M300-05 (I
don't know why it's not the M300-10, but then again, this was a 2nd
hand machine ~5 years ago, and it's of no help so far). I'm running
dos 6 and win 3.1 on this pc, but it's mainly used in dos. (Dosshell
text editor, and dos based modem program).

In the end, I only want to get this pc up and running long enough to
get a pile of text files off the HD, and then my relative will likely
not use the machine anymore if it's becoming this unreliable (though
he's quite attached to it). But the 1st need is to get at the HD. Any
help would be most welcome.

Thanks