Screen white and light flashing

Hello friends! I had this exact same issue and have since done a full repair on my device. The problem is that the Libra boot sequence fails once the update fails, this makes it impossible to boot or even charge. I will do my best to give a detailed walk-through here and outline the couple conditions that arose for me.

I highly recommend finding an SD card adapter, gathering your tools, and requesting an image from the MobileRead forums before starting the repair. Not a big deal to open it up first but it did take a couple weeks since I kept halting my progress at every step of the way due to being unprepared. If you're wondering about the tools or the forum read the guide below and you should see what you need.

The first thing to do is take apart the Libra 2. I initially got into the back of my case by using a guitar pick to carefully pry up the edges until the case came free. Any thin plastic shim will work.

Once open there are three main sections: the battery, the main board, and the power switch.

Uninstalling the microSD card:

If you're having a hard time getting the card out there are a couple tiny openings on the back that you can try gently but firmly applying pressure to. I'm pretty sure I punctured the back of my old SD doing this and killed it that way, so proceed at your own risk.

Then go to this thread and request an image for the Kobo model. In my case I have a Libra N418 which can be found as the first few digits of your serial number.

Once a helpful user sends you the files via PM there will be multiple board revisions and you will have to select yours. I have 6F0 also known as rev F. You can see that on the board here as the last 3 values:

I then downloaded that file ("Kobo_Libra....rev_F.img") and used Terminal (MacOS) to copy the microSD card image over to the corrupted card. This will overwrite all data on the corrupted card.

But wait! The file that comes from said helpful user will have an incomplete serial number. You can choose to proceed anyways and your e-reader will be bootable but unable to connect to the network in anyway, including the Kobo Store and Libby/OverDrive.

I wanted to connect to my library so I had to fix this using a hex editor. I chose to download ImHex because it seemed user friendly and I had never done anything with hex before. It worked great, I am sure you can find other tools that work just as well.

The serial number is located at 0x200. My image was set to N418xxxxxxxxx and I manually changed those x's to my own serial. Save the .img in it's corrected state and copy the file to your sd card.

If this doesn't work or the data seems unchanged that is because of one of two things. Either the sd card adapter is stuck on "read only" indicated by the switch here:

READ ONLY

WRITE

Otherwise, as with my card, it is physically failing and you have to use a new card, which works just as well.

At this point your sd card is back in a bootable state. When you first turn it on it may have issues connecting to the internet. I fixed that by updating the e-reader and then factory resetting it through Settings -> Device information -> Factory reset your eReader. This returned full functionality to my Libra 2.

Yay! Congrats! If you've made it this far you've helped saved another device from the e-waste bin. This was really tough for me to figure out my first go so I hope this level of detail helps others.