A damaged ePaper display (EPD, the screen panel itself) is fragile and can easily be broken via physical damage, including the ribbon cable that connects it to the PCB internally. Cracks are the most obvious sign, but sometimes are only visible once the device has been open and the back of the EPD inspected.
Many screen problems are not the panel, though. They come from the battery, the main board (PCB), WiFi or firmware, and those are often a quick fix. This guide provides examples of when the screen was the issue.
An ePaper screen keeps its last image when there is no power at all. A screen that shows an old picture and never changes is usually not broken. The device has likely stopped waking up to retrieve new images.
Signs the screen may be damaged
All photos below are from TRMNL X, but the same signs apply to TRMNL OG.
Only part of the screen updates. One half or one block of the screen changes with each refresh, and the rest stays on an older, faded image. The line between the two parts is sharp and stays in the same place. This is a distinct failure "look" compared to a PCB or Firmware issue related to screen updates and should be confirmed by inspecting the back.
Speckles or grain across gray areas. Gray areas look sandy, with fine light and dark dots that do not clear after a full refresh. This is consistent across screens and even through a screen wiper run.
Lines, streaks or spots that never move. Thin lines or dark spots stay in the same place on every screen, often near the edge of the panel. Edge damage like this usually comes from pressure on one point.
Overlapping images, dark blocks and blank areas. Parts of the screen mix several old images, show solid dark blocks or thin vertical lines, and other parts stay blank.
A shadow that stays after heat. A gray patch stays in one area of the screen and does not clear with a full refresh. Direct sun, a heater or a hot car can cause this. ePaper does not recover from heat damage.
Signs it is probably not the screen
The whole screen is frozen on one image or stays blank. This is almost always power, WiFi or firmware. Follow Troubleshooting an Unresponsive Device or the step-by-step device troubleshooter.
A faint copy of the previous screen (ghosting). This is normal for ePaper and clears with a full refresh.
Grays look washed out or uneven over the whole screen. Try a different temperature profile, see Tuning a washed-out display.
The device only works when plugged in, or will not charge. This points to the battery, the dock or the PCB, not the screen. Troubleshooting an Unresponsive Device.
If you are not sure which one you have, contact us before you order a part. Send a photo of the screen and we will tell you what we see and what other tests we can do to build confidence in the issue. A new screen does not fix a board or battery problem.
Replacing the screen
You can order a new screen from Replacement parts. Then follow the guide for your device:
TRMNL X: How to Disassemble your TRMNL
TRMNL OG: How to replace your internal components
Handle the new panel by its edges and never press on one point. On TRMNL X, do not close the case until the screen sits flat inside all 4 ribs, or it will crack. This is the step people miss most often.
Not comfortable opening the device? Contact support and we can repair it for you.