Looks like I'm stuck with a non-useable hard drive, but while no effective answers elsewhere thought someone knowledgeable of hardware might have a helpful suggestion.
Messed-up my hard drive by trying a loopback procedure which didn't work, and now whenever have completed a new full install on this hdd, with everything going smoothly right up to final re-boot, the screen that comes after this 'booting from hard drive' has nothing on it but a flashing cursor. Have tried full wipe [seemed to just make it worse -- less on boot-up screen from previous just 'grub loading, please wait'; but never loading], and several re-installs, but after move to the hard disk from install disk, just get nothing.
Any thoughts at all greatly appreciated.

I doubt you can mess up a drive by that. Might have gone bad on it's own.

I'd be tempted to run smart tests or get the OEM diags and run them.

Might also run memtest for a day.

Grub loading may be some issue with a damage to the first part of the drive. It might be fixable.

It's surprising that would happen on a machine with only one operating system if you accepted all the defaults during the install. Is this one of the Ubuntu derivatives? Did you do an mbr or GPT install?

The blank screen with flashing curser in all of the installs that I've done, was due to graphics driver. What OS are you running? Also do you know which graphics card the machine uses

Am using openSUSE; video card is Vesa-Vega [Twinhead], and VGA chip is ATI; did all installs: default, mbr, separate boot partition, and just /.
Do believe is now damage to first part of drive [on some 'rescue disks' ended with 'x not found, kernel panic'], but how do you fix it???

Did you run smart tools diags from the OEM?

OEM never provided smart tools or even made repair or maintenance manuals available, or even a simple schematic; they insist all help must come from authorized service providers -- at high cost.

What OS are you installing?
Do you have a live-cd?
If so post output of

I mean OEM like hard drive maker. Example would be seagate drive, go to seagate web site and get diags. If not then get generic drive diags or use linux diags.

Hi,

You can look at these links for useful tools;
Plus these are some useful Recovery & diagnostics;

Hope this helps.
Have fun & enjoy!

Will work on the diags; using openSUSE OS; using live and system repair disks, have tried to obtain a grub prompt for a manual boot -- but can't do it.
Live disk [freespire, repair disks, etc.] either just give same blinking cursor as previous, or get nowhere until 'kernel panic'.
Trying: mkdir /mnt/sda4 then: mount /dev/sda4 /mnt/sda4 gives response 'bad superblock on /dev/sda4 -- missing codepage or helper program or other error'.
Trying: mkdir /mnt/temp then: mount /dev/sda4 /mnt/temp gives response 'sda4 is write protected, mounting read only' then: chroot /mnt/temp gives 'failed to run ?/bin/bash? no such file or directory
Trying: chroot /mnt/sysimage gives 'no such file or directory'
Trying: mkdir /mnt/sda4 then: mount /dev/sda4 /mnt/sda4 then: grub-install --root directory~/mnt/sda4 /dev/sda gives response 'can't with a parameter; use grub-install.unsupported [get: no such file or directory] or call "yast2 bootloader" [get: no such file or directory].

The fact that even live cd can't get booted [but install disk can; and repair disks can] so can press ESC and "c" for a Grub prompt, shows how bad off this hard disk's lead-in is.
Will concentrate now on getting the diags [believe it is an hitachi, but will remove and double check.
Also will try to get that UBCD Ultimate Boot cd.

With 1 OS I doubt you have a /dev/sda4. Try /dev/sda1

"The fact that even live cd can't get booted"

Run memtest. Be sure to make note of amount of ram mentioned in test. Is it correct?

I typically install 11 or 12 partitions; sda4 would be Extended; my laptop uses cartridges into which you place the hard drives so can swap them in and out in seconds, and no problem when using other hard drive in this laptop, and ram is fine.Am going to make floppy and burn the linux option for that downloaded hitachi smart tool and see if info helps.
Thanks for all the attention; has certainly been a learning experience.

You still wouldn't mount the extended you would mount the partitions within it.