Here's everything I could find on the proper procedures:
Do not try to flash dash cams with incompatible firmware. For example, if you have a 3-button dash cam, do not use this firmware. If your existing firmware does not end in T2L-KH, do not use this firmware.
Firmware Backup
Before updating your firmware, it is highly recommended to backup your existing firmware. This can be easily done using the following method.
Download the Backup autoexec.ash file. This is a simple text file with the following contents (firmfl gen 5 bst bld pri rom dsp d:\backup.bin). This file has the necessary commands to extract the existing firmware from the dash cam.
Make sure the camera battery is fully charged
Use the following settings in your dash cam:USB – NO (USB IN – NO),Delay. – NO (SHUTDOWN – NO), Auto save – OFF (MOTION DET. – OFF) A.SHUT. – OFF (AUTO OFF – OFF)
Format the SD-card (via the dash cam or your computer).
Copy the autoexec.ash file to your formatted SD-card. DO NOT copy the autoexec.ash file to the DVR’s internal memory, only to the SD-CARD!
Insert the SD-card with the autoexec.ash file in the dashcam and turn it on. The dashcam will be in normal standby mode. The process to backup the firmware takes about 10 seconds. However, we recommend that you wait 1 MINUTE.
After waiting a minute, and turn off the dash cam.
Insert the SD-card into the computer.
Copy the firmware stored as BACKUP.BIN
Rename the resulting BACKUP.BIN in accordance with the number of your firmware. For example, “V8.9 T2L-KH.BIN”.
Simple Firmware Update Instructions
You must use an SD-Card reader to perform this operation. Do not attempt to do this directly on the dash cam.
Download the desired firmware from the section below.
Rename the downloaded firmware file to yamaha.bin
Copy the file yamaha.bin on SD-card using a card reader.
Insert the card into the dash cam and turn it on. You should see a running circle and the inscription “Firmware update”.
Do not turn off the dash cam until the symbol and the words disappear from the screen, the whole process takes about 10 seconds.
You should see a message to turn off the dash cam. Turn it off, remove the memory card and delete the yamaha.bin file.
Use your dash cam with the latest firmware.
Complete Firmware Update Instructions
You must use an SD-Card reader to perform this operation. Do not attempt to do this directly on the dash cam.
Download the Update autoexec.ash file. This is a simple text file with the following contents (rm a:\autoexec.ash
firmfl prog d:\firmware.bin >> d:\flashlog.txt
rm d:\autoexec.ash
rm d:\firmware.bin
). This file has the necessary commands to extract the existing firmware from the dash cam.
Download the desired firmware from the section below.
Rename the downloaded firmware file to firmware.bin
Copy the autoexec.ash and firmware.bin files to SD-card using a card reader.
Insert the card into the dash cam and turn it on.
Wait a minute for the process to complete (the whole process takes about 10 seconds).
Turn off the device
Use your dash cam with the latest firmware.
Latest Firmware
These firmware files are only compatible for cameras that have an existing firmware of v2.24 T2L-KH to v7.8 T2L-KH. IF THE CURRENT FIRMWARE IN YOUR DASH CAM DOES NOT END IN T2L-KH, DO NOT UPGRADE YOUR FIRMWARE.
The latest firmware is version 8.9T2L-KH. Click the following link for the latest firmware version. V8.9 T2L-KH
Previous Firmware
Click the appropriate link to download any of the previous firmware files.
V7.8 T2L-KH
V7.4 T2L-KH
V7.1 T2L-KH
V6.8 T2L-KH
V5.8 T2L-KH
V5.5 T2L-KH
V4.4 T2L-KH
V3.6 T2L-KH
V3.4 T2L-KH
V3.2 T2L-KH
V3.1 T2L-KH
V2.6 T2L-KH