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Firmware version 00.96.607B is not supported by OpenWrt, while versions 00.96.601J and 00.96.607J have been tested and confirmed to work. Other versions, such as 00.96.608S, have not been tested. This router has been distributed to both ADSL and fiber users, so there may be multiple firmware versions that are not documented. Users can attempt to flash OpenWrt on other versions, but it is recommended to create a backup of the stock firmware to allow rollback in case of issues.
in installation snapshot with no luci is listed . for first time install a stable image with luci is going to be better.
in Installing OpenWrt - BRNBoot Recovery web interface (easy) i found that the routed won’t load the rescue.bin unless it’s the only item on a folder
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The VRV9510KWAC23 supports a TFTP-based recovery mechanism. To use it, set up a TFTP server on a PC (for example, Tftpd on Windows or tftpd-hpa on Linux). Rename the OpenWrt initramfs image to rescue.bin and place it in the TFTP server’s root directory.*
*The router will only load the rescue.bin file if it is the only file in the TFTP folder. To initiate recovery, power on the router while pressing the SERVICIO button; a blue LED should illuminate. This process is useful if the router becomes unresponsive or “bricked.”
for advanced users swapping between the stock FW version is possible but requires extra hardware to be done as shown in this video https://www.youtube.com/watch?v=koZMzVCAAuE