Which or chip is currently inside your T3?
Ensure the .bin firmware file is placed directly in the root directory of the MicroSD card (not inside any folders).
| | Likely Cause | Fix | |---|---|---| | Printer ignores the firmware file | microSD card not FAT32, or file not named firmware.bin exactly | Re‑format the card (FAT32, 4096 byte allocation), re‑copy the file. | | LCD stays blank after power‑on | Wrong firmware file for your mainboard revision | Confirm you downloaded the correct file for the Sunlu T3 (not a different model). | | Printer freezes during update | Power interruption or corrupted firmware file | Repeat the update with a freshly downloaded file and a stable power source. | | Z‑offset or bed leveling lost after update | This is expected behaviour | Re‑do the paper‑test Z‑offset and run a new ABL mesh (see next section). | | Jam detection triggers falsely | Known bug in V3.40 firmware | Turn off jam detection in the LCD menu ( Configuration > Jam > OFF ). | | Extruder cooling fan stays off when hotend is heating | Stock firmware fan pin mapping issue | Consider switching to the community Marlin build (see Advanced section). |
Updating your is a critical maintenance step that can resolve common "out-of-the-box" bugs, improve print stability, and unlock advanced features like refined high-speed printing . Whether you are sticking with official releases or exploring custom Marlin builds, this guide covers everything you need to successfully update your Terminator 3. Why Update Your Sunlu T3 Firmware? Sunlu T3 Firmware Update
displayed on your screen? Are you running the standard Sunlu T3 or the T3 Plus ?
You will need a microSD card (the small one, not the full‑size SD card) formatted to FAT32 . Most cards 32 GB or smaller work fine. Using a fresh or freshly formatted card prevents file‑system conflicts that can derail the update.
A MicroSD card (8GB or 16GB is ideal, formatted to with a 4096-byte allocation size ). Which or chip is currently inside your T3
The printer bootloader only looks for new files. If it detects a file name it has seen before, it skips it. Rename the .bin file. Also, verify that your SD card is under 16GB and properly formatted to FAT32. Moving Beyond Marlin: Consider Klipper Firmware
Re-format the SD card to FAT32 with a 4096-byte allocation size.
(Used when SD update not supported or using custom Marlin build.) | | LCD stays blank after power‑on |
However, be aware that moving to Klipper is a more advanced project. It requires setting up a Raspberry Pi, compiling your own firmware, and manually configuring your printer's parameters. It’s also worth noting that flashing Klipper will replace the stock firmware completely, and your printer's LCD screen may not function in the same way. For those who love to tinker, though, Klipper can breathe entirely new life into the Sunlu T3.
Ensure the file ends strictly in .bin . Make sure the card is under 32GB and successfully formatted to FAT32. Try renaming the file to something short, like firmware.bin . Blank Blue Screen (Bricked State)