LizardMan--the instructions at http://wiki.openwrt.org/toh/buffalo/wzr-hp-g300h in the 'OEM installation using the TFTP method' section will work if your device is not otherwise damaged. One thing I'm not sure of is which MAC address you should set with the arp command. On the few occasions I've actually tftp'd an image to my G300H, I've had to try a few different things. I believe I use the SSID on the label. Also, not sure about the A2 F0B, but I've got the A2 A0 and I need to use trunk that I get at http://downloads.openwrt.org/snapshots/trunk/ar71xx/. The A2 A0 has the rtl8366rb switch so Backfire doesn't work.
If you think your device is physically ok, I'd definitely take the time screwing around with tftp to get OpenWRT on it. Mine works great, and once you've got it going, you can use sysupgrade images to do subsequent updates. I install luci and load the .bin right through the web interface.
The latest official Buffalo DD-WRT loads fine using tftp. The kernel probes show this unit uses the rb style LAN switch hardware. However, the 10.03.1 FW should support it. I just can't find a way to load it. Buffalo seems to have locked down these A2 F0B units. It rejects all attempts to use anything but their .enc files.
I've tried the tftp method:
Set static arp for the MAC used by the uboot firmware
Set computer IP addr to 192.168.11.2
Power up router
Send FW using tftp in binary mode
If I use the 15MB *.enc FW file from the Buffalo site (latest Alpha code on their site) it works fine. I've flashed using this method several times. It's the only way to recover from attempts to use the mtd flash update method.
If I use a 3 to 4 MB OpenWrt squashfs or jffs file the router never responds to tftp write request probes. It just sits there. It ignores tftp, unless it's a .enc file. If I understand the last 16 pages of this thread correctly, this is because the uboot FW checks for the a header in the enc file. I could turn that check off, if I had access to the uboot env tool, but it's not included in the DD-WRT version (.enc file) available from the Buffalo site. Chicken and egg problem.
Load the Buffalo .enc DD-WRT FW
Transfer a copy of sysupgrade OpenWrt to /tmp on router
Write file to flash using the mtd command as shown on the OpenWrt site for this router
"mtd -r write OpenWrt-firmware-file linux'
Wait while new FW is written and router reboots.
I've tried this many times. It seems to work, except the router reboots to a Diag LED on solid and never turns off. I've waited an hour for it initialize and reformat jffs, but nothing happens. It just sits there with the green LED on (power symbol), red diag LED on, and an LED at the bottom (blue?).
After 30min to 60min I've power cycled it, it goes back in to the same diag LED solid state. The only way to recover is use the official Buffalo .enc DD-WRT image with tftp. This works every time. I've used the tftp transfer method with their FW file many times. It's rock solid, but only if I use their file.
I don't want to use DD-WRT on this router. I've used DD-WRT for years on many routers (WRT-54GS, WRT-54G and WHR-HP-G54). However, I've never found a version of DD-WRT that is stable on this router in N mode, never. It locks up and/or drops wireless clients.
I've used DD-WRT for years. It's not in current development, and attempts to use the large flash space in this router with ipkg (no opkg) fail with a file system R/O error. I find the endless mass of NVRAM variables admin process a mess. The OpenWrt overlay file system is nice!
I'm moving away from DD-WRT in general. I've loaded OpenWrt on WHR-HP-G54 units, it works but leaves little flash/jffs space for loading additional programs (IPv6 tunnels, IPv6 utils and VPN code). This router has far more flash and RAM, but I haven't found a way to load OpenWrt on it, because Buffalo locked uboot down to prevent loading and/or using it.
I don't understand why the mtd method doesn't work. I've tried it several times with both squashfs and jffs files. I found a slightly different mtd command on another board (adds -e linux), it erases the linux FW area first, before writing. Using either mtd method the diag LED comes on solid and the router never reboots. It's like the uboot code looks for a signature in the linux area before jumping to it, and only the Buffalo blessed FW images have this signature. Their FW files are much larger. Maybe they use a large file to initialize and write a signature across the entire flash area, a signature their uboot code looks for, before it jumps to the FW in flash.
This product has never worked correctly. From day 0 it has dropped or locked up if setup in N mode. The latest Buffalo DD-WRT FW works if I disable N mode. However, it's an N router and that FW will not allow me to load additional tools. I purchased this unit for N, its large flash and RAM for progs/utils and gigabit interfaces. Only the gigabit interfaces actually work, N doesn't and the extra flash space is useless with their DD-WRT.
I sent my first unit back to Buffalo (RMA) because it locked hard (unresponsive even on the wired interfaces) if in N mode. They sent this replacement a long time ago. It too locked up in N mode, so I ran DD-WRT in G mode. A few weeks ago I loaded their latest alpha version, which works a bit better, but drops N connections. It doesn't completely lock up, but it's not stable in N mode either.
I need to find a way to break out of Buffalo's locked down uboot code. It rejects all tftp transfers that aren't .enc files and rejects non Buffalo FW written to flash with mtd.
Why? This will only drive people to stop purchasing their products. It's not like their FW actually works. This unit has been a major pain from day one, and has never worked correctly. Their WHR-HP-G54 units worked so well. I have several of them and helped people use DD-WRT on them for years.