flashing uboot from within linux or from uboot itself is pretty easy and painless...
If you can get it booted, thats the fastest way to go... have you tried a sniffer on your network to see what's happening? Wireshark is a good bet ... see if you can detect any activity from your box ...
Did you change anything on your network or change any uboot env values that would have cause it to no longer boot?
If you can't boot it (EDIT
: or connect to it w/ netconsole or serial - see Kuroguy's excellent comment below! He makes a very good point...) , then JTAG would be your only option. It isn't as difficult as it looks to use JTAG ... the first time it seems hard, but after one flash and after you have stuff set up, it is pretty easy ... though soldering takes some time to do carefully.
There is a guide here : http://buffalo.nas-central.org/index.ph ... /Openwince
LS1 (foonas, nfs, Tranmission
print server, Firefly
for my Roku
Various LS-Pros v1,v2 (unbricked w/ serial & jtag)
KuroPro, LS2 & KuroHG (foonas)
Working on davysweather.dyndns.org
lately... => wooohooo!
Unknown command 'wooohooo!' - try 'help'