Experimental: a fix to test for the blank screen on the Heltec V4 with Expansion Kit V1. Not yet tried on a kit. Please tell us what you see.
What's in it: Cairn 126 for the Heltec WiFi LoRa 32 V4 on the Expansion Kit V1 (2.8" touch screen), with one change: the kit's power switch (GPIO 36) is now held the way Meshtastic and MeshCore hold it. Earlier Kit V1 builds (Cairn 121 to 126) turned it the other way, which can leave the screen blank while the radio itself runs.
What experimental builds are. Use MeshCore-HeltecV4KitV1-Cairn126-2026-11-02-test1-full.bin.
Cairn 126 for the Heltec V4 + Expansion Kit V1 -- test 1 (2026-11-02)
For the Heltec WiFi LoRa 32 V4 (ESP32-S3R2, 2 MB PSRAM, 16 MB flash, SX1262) on the Expansion Kit V1.
Not for the V4-R8 on the Expansion Kit V2: that board has its own build in the Cairn 126 release.
Nothing in it can damage the board, and you can always flash Meshtastic or MeshCore back.
File: MeshCore-HeltecV4KitV1-Cairn126-2026-11-02-test1-full.bin
FLASH IT (Chrome or Edge on a computer)
1. Open https://espressif.github.io/esptool-js/
2. Plug the V4 in with a USB-C data cable. Click Connect and pick its port.
No port, or it won't connect: hold PRG, press and let go of RST, let go of PRG, then Connect again.
3. Click Erase Flash and wait for it to finish (this clears the other firmware's settings).
4. Flash Address 0x0, the -full.bin above, then Program.
5. When it says done, press Disconnect, then press RST.
WHAT TO TELL US
- Does the screen show a picture now? Does touch work?
- If it is still blank: is the backlight on (the screen glows) or completely dark?
- A boot log helps either way: open a serial monitor at 115200 baud, press RST, and copy the first
60 lines or so.