Kobo Aura H20 frozen screen issue

[nopsled]

Hi everyone,

I have a 1st edition Kobo Aura H20, which has a frozen screen as if it's not refreshing itself. The device was updated to the newest firmware over wifi and used a few times after the update. Then after a couple reading sessions the reader display was stuck and only showed blank white background and a small artifact in the top right corner. The white LED is blinking on power up and lights up afterwards. Screen backlight also works. The reader was not physically damaged. Also, the reader is not recognized as a block device when connected to a computer, it does not come up in the output of lsblk nor lsusb. At one point when I connected the device to a PC the white screen randomly changed to the home screen and never updated itself again.

My attempts so far have been the following:

• Charged it a few hours and tried to do a factory reset and power cycles.
• Then I thought it was a botched update, so I carefully opened it up, backed up the contents of the internal SD card, attempted to downgrade using the official firmware, i.e. copied the firmware files under the .kobo directory. Next power cycle took longer as if the update was happening, but no change to the screen itself.
• Next, I copied the dumped firmware to a new card, maybe it had some bad sectors or had issues booting. No changes to the screen at all.
• Requested a new firmware from the kind folks on the forums. Mirrored the image to a new SD card. Tried it with the new firmware image, same end result. It seemed like the reader was working, but again, no changes to the screen.
• Ordered a replacement screen, figured it was busted. When the new screen arrived, I connected everything up and the new screen never refreshed. It is stuck on the image they've tested with. While it might be a faulty screen, they claim all their screens are tested and I don't think this is the issue here.

I am currently at the end of my wits. I'm not an electrical engineer, I don't have the know-how nor the equipment to probe anything on the PCB. I saw no visible damage at all on the PCB, no busted components, no corosion damage on the joints. There is a slight, barely noticable heat coming from the microprocessor indicating that some background processing is happening. None of the other ICs seem to produce any noticable heat.

Is there any way I can check if the display driver (TPS65185) is good/faulty without some fancy equipment? I only have a basic multimeter that I can't attach to the IC pins. The PCB does seem to have some test points, but I have no clue what's what though. Are there any other components that might be at fault here that are handling the refreshing and drawing on the display?

Any ideas how can I save this e-reader? Thank you all for the help!

[alex180500]

I have the same issue with a Kobo Glo HD and also want to know if anybody knows how to test these displays!