Problem reinstalling Xubuntu 16.04

[MR ZenWiz]

I have a spare HP NW9440 laptop that I had running 14.04 for a while.
I replaced it with an 8710W a few years ago (that was recently stolen
and replaced) and hadn't used it in a while. I installed 16.04 on it
as a backup laptop for a good friend of mine, then it sat unused for a
while again.  Then I took out the drive with the intent of adding it
to my newer replacement notebook.  It seemed to work fine there

Now I can't install on the NW9440.  It failed part way through
installation on the replacement hard drive I put in. I thought it
might be the disk, so I put the previous one back, but it won't
install there either.

I tried using a USB flash drive and a DVD for the install medium, with
and without a network connection.

It gets to the "downloading 46 of 87 files" mark and all disk activity
stops, the cursor wheel stops spinning and it never gets past this
point.  I've waited for up to half an hour before giving up.  If I use
a network connection, that remains alive and flashing, but nothing
happens.

The mouse moves, but clicks generate no response, and nothing from the
keyboard works either.

I've tried adding noacpi and nomodeset to the boot command line, and
I've used the live CD/USB version to blaclist the tpm_tis driver
(which was also complaining for a while).  The PROM's TPM setting
makes no difference (enabled or disabled).  No noticeable effect.  I
even restored the factory defaults in the PROM.  Still nothing.

Given that this happens with both the USB and DVD media, I'm pretty
sure it isn't either of them. That leaves memory, CPU, m/b or disk
controller (m/b also).  Is there anything else?

What kind of tests can I run to determine what is causing this?  There
are a few diagnostics in the boot PROM, but I'm not sure which would
be of any use.  Are there any PROM settings I should look out for in
particular?

Thanks.
MR