http://archlinuxarm.org/platforms/armv6/pogoplug-provideov3#qt-platform_tabs-ui-tabs2 especially the last section "Hey! it stopped working"
This will boil down to
on a different computer/VM
1/ format a new usb drive with ext2 and journaling
2/ copy the rootfs to it (use the 2012-05 if you did NOT update the kernel this summer, the latest rootfs if you did)
3/ assign a MAC address (create the usr/local/mac_addr file and copy the HW address as printed on the foot of the plug)
if your plug is still able to boot the original firmware you can also just rerun the initial alarm install process
Boot the plug with your new usb drive, on you client computer clean up the previous ssh keys (most likely stored in ~/.ssh/known_hosts in linux or Mac, on windows you'll get a dialog telling you about a probable security breach and whether you really want to connect to that host with an ID that does not match the records, in this case say YES)
go for your 3 steps update process before installing software :
Possible step 0: IF you did NOT update your kernel then you most probably need to do it before anything else and certainly before rebooting.
$this->bbcode_second_pass_code('', 'cd /tmp
wget [url]http://us.mirror.archlinuxarm.org/os/oxnas/update-oxnas.tar.gz[/url]
tar xf update-oxnas.tar.gz
cd update-oxnas
sh update-kernel.sh
')
Step 1:
$this->bbcode_second_pass_code('', 'pacman -Syu --ignore glibc ')
do you want to update pacman first ? => No
accept the conflicting package replacement (from the top of my head you want to remove libsystemd and replace it with core/systemd)
Step 2:
$this->bbcode_second_pass_code('', 'pacman -R pcmciautils ')
pcmciautils has a foothold in /lib that prevents glibc from updating. You *may* need to reinstall it afterwards, but for me it works well without it.
Step 3:
$this->bbcode_second_pass_code('', 'pacman -Su ')
updates glibc and possible packages that depend on it
reboot and customize to your needs.
HTH