Fix KOReader After Firmware Update

Depending on how you installed KOReader on your device (for instance, if you access it via NickelMenu), there may be different update steps to follow to re-access your mods and software after the device has undergone a firmware update.

The following page has helpful information: https://github.com/koreader/koreader/wiki/Installation-on-Kobo-devices#what-about-official-firmware-updates 

If Using NickelMenu

1. Go to this page on the MobileRead forum. There will be a set of links for "one-click" Kobo packages. If you are just repairing your install after a system firmware upgrade, only download the KFMon package. These packages are updated relatively frequently.
2. Now, go to this other page, in which the developer has supplied a set of easy-to-use scripts for updating your Kobo. Download the appropriate script for your OS (due to the web browser opening the PowerShell script as a tab rather than a script, I used wget [URL] -o install.ps1 to download the script properly). Put the script and ZIP file in the same folder. Do not unzip.
3. Plug your Kobo into your device, allowing your OS to access the Kobo's filesystem, and run the script. Select the correct option in the script when prompted, and allow it to run.
4. Once it's finished, eject the Kobo cleanly using your OS's "eject external storage device" options, and allow the Kobo to reboot as needed.