Failed firmware update to AP9631

[ocgltd_apc]

I just bought a used AP9631 to go into my Smart UPS 1000.  The firmware is quite old (5.17, bootload 1.2) so I am trying to upload new firmware using the FTP method but the transfer keeps failing as shown below.  I did a factory reset on the AP9631 and tried again, no difference.

Can someone suggest what's wrong and what to do differently?

ftp> cd /
250 CWD requested file action okay, completed.
ftp> dir
200 PORT Command okay.
150 File status okay; about to open data connection.
--wx-wx-wx 1 admin admin 2288640 Nov 22 2011 apc_hw05_aos_517.bin
--wx-wx-wx 1 admin admin 2190196 Dec 1 2011 apc_hw05_sumx_517.bin
-rw-rw-rw- 1 admin admin 45000 Feb 1 16:26 config.ini
drwxrwxrwx 1 admin admin 0 Apr 21 2010 db/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 ssl/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 ssh/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 logs/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 sec/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 dbg/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 lang/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 upsfw/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 rms/
drwxrwxrwx 1 admin admin 0 Oct 10 2012 scg/
226 Closing data connection.
ftp: 877 bytes received in 0.03Seconds 31.32Kbytes/sec.
ftp> cd /upsfw
250 CWD requested file action okay, completed.
ftp> put d:\temporary\ups\bins\apc_hw05_sumx_708.bin
200 PORT Command okay.
150 File status okay; about to open data connection.
426 Connection closed; transfer aborted.
ftp: 1671168 bytes sent in 39.76Seconds 42.03Kbytes/sec.
ftp> put d:\temporary\ups\Bins\apc_hw05_aos_708.bin
200 PORT Command okay.
150 File status okay; about to open data connection.
426 Connection closed; transfer aborted.
ftp: 1671168 bytes sent in 39.48Seconds 42.33Kbytes/sec.
ftp> put d:\temporary\ups\bins\apc_hw05_bootmon_109.bin
200 PORT Command okay.
150 File status okay; about to open data connection.
226 Closing data connection.
ftp: 262144 bytes sent in 5.38Seconds 48.76Kbytes/sec.
ftp>