The WRT610N v1.0 is based on the Broadcom 4705 cpu running at 300MHz. It has 8 MB flash and 64 MB SDRAM (2x HY5DU561622FTP).
The WNICs are a dual BCM4322 Chipset, one for 5GHz A and N and one for 2.4GHz B,G and N. The switch is a BCM53115 chip.
The WRT610N runs 802.11 A, B, G, and Draft N wireless protocols. It provides 4 gigabit LAN ports, 1 WAN port and a USB 2.0 port.
You should see a “Management Firmware update” screen. Give it the openwrt-wrt610n_v1-squashfs.bin or openwrt-wrt610n_v2-squashfs.bin file depending on hardware version.
If you have a serial console and the above isn't working you can press ctrl-c while the router is booting to get to a CFE prompt, then either:
nvram set safe_mode_upgrade=on
flash -ctheader -https : flash1.trx
even though CFE says it's doing that last bit, it appears some setup is missing. Running the command manually from a canceled boot and then browsing to the upgrade page shows an immediate “Update Success” and the router reboots (CFE reports that it has run the “reboot” command).
OEM installation using the TFTP method
Upload the openwrt-wrt610n_v1-squashfs.bin or openwrt-wrt610n_v2-squashfs.bin image with TFTP.
describe actual method
Based on the CFE boot logs, it appears that the router attempts to load something via tftp with a max size of 0x32000 bytes (3.625MiB) into ram. This would limit our image size quite a bit.
If you have already installed OpenWrt and like to reflash for e.g. upgrading to a new OpenWrt version you can upgrade using the mtd command line tool.
It is important that you put the firmware image into the ramdisk (/tmp) before you start flashing.