Yesterday my WL-500G had the same symptoms like below after playing with NVRAM. The restore utility doesn`t work but i found a great solution (Thanks JockyW:http://wl500g.info/showthread.php?t=1451&highlight=dead

Recovery!!:
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1. pull power cable and wait 20 seconds
2. keep button pressed and connect power cable: power led should flash
3. ping 192.168.1.1 should reply else redo steps 1 and 2
4. run Asus Firmware restoration tool, select firmware file (e.g. wg01080109_WL500g_EN.trx) and press upload.
After some seconds press the Abort button or wait until it says "Upload fails! Please check the connection"
5. from a dos box or linux console run: tftp -i 192.168.1.1 put wg01080109_WL500g_EN.trx
6. tftp returns something like: "Transfer successful: 3731456 bytes in 2 seconds, 1865728 bytes/s" if it doesn't redo steps 1-5 (sometimes I needed three or four times before it worked)
7. after ca. 80 seconds your Asus should reboot

I did this procedure with
1. wl500g-clear-nvram.trx
2. wl500g-recover.trx
Then I could flash any firmware and the device was alive again.....

ciao,
jbk