What's working for me on my Kobo Aura H2O is using the suspend.sh script from pbchess.
Download latest build from here:
http://forum.vlasovsoft.net/viewtopic.php?f=8&t=537
Only edit I do is to comment out the wifi line, like this:
Code:
#. $ROOT/wifi_off.sh
Replace the suspend.sh file in the koreader directory with this file from pbchess. (Preferably keep the other file as a backup by renaming it)
You will have to replace the file again after every update as it will be overwritten with the original file.