Thanks for pointing out what I missed! Now I'm a traitor for going back to windows

http://tablets-dev.nokia.com/maemo-d...-downloads.php is 404, but I had the maemo_flasher_3.5_2.5.2.2.exe lying around, so I ended up using my Win8.1 laptop. I had to follow the advice in
http://talk.maemo.org/showthread.php?t=82822
http://talk.maemo.org/showpost.php?p=849980
for getting libusb-win32-bin-1.2.6.0, installing the driver, then the usual
flasher-3.5 -F RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin -f
unplug, pop the battery, then
flasher-3.5 -F RX-51_2009SE_21.2011.38-1_PR_COMBINED_MR0_ARM.bin -f -R
worked.