E5 V3 per the Gemini firmware release-notes PDF (2024-05-20). Exact build number is shown in the device menu / on the download page. Update help page body was a single oversized minified line (Paligo docs) not machine-readable in the sandbox, so steps below are from Litepanels' corroborated published docs.
steps
what you'll need: USB-A flash drive (.hex file) inserted into the panel; update triggered from the menu
1Download the firmware .zip from litepanels.com/en/product-support/firmware-updates/download/ and unzip to get the .hex file.
2Format a USB drive as FAT/FAT32 (use 'MS-DOS (FAT)' on Mac). exFAT works only with an MBR partition table; GUID-partitioned drives will NOT work.
3Copy ONLY the .hex file to the root of the USB drive.
4Insert the USB into the Gemini's USB-A port.
5Press MENU > Settings > Firmware Update (or hold MENU while powering on); select the firmware file.
6Update runs ~1 minute: power LED flashes yellow, then alternates red/green, then the panel reboots.
WarningGUID-partitioned USB drives fail, must be FAT/FAT32 (or exFAT with MBR).
WarningDo NOT interrupt mid-update; if power is lost it can reboot on the previous firmware, just restart the update.
WarningOn Mac, don't re-insert a freshly formatted drive into the Mac before copying the .hex; copy the file straight after formatting.
GotchaIf an update fails, reformat with fresh MS-DOS FAT and retry with only the .hex on the drive.