In my experience with this router, the failsafe doesn't actually work. I have 2 of these devices that I use for experimental purposes, and I have ended up in seemingly bricked situations a few times (sometimes it was expected, other times it was a surprise. I have not tried using the serial port (mostly out of laziness), but when this has happened, the only way that I have recovered from a complete lack of network connectivity on these devices was to do the pin-short method. This is generally a bad idea most of the time and for most devices, but if all else is lost and the router would just be e-waste, give it a shot. Do it carefully so you don't short the wrong pins.
Prep:
- download the firmware you want to flash onto the device.
- set your computer to a static IP in the 192.168.1.0/24 range (anything but 192.168.1.1)
- start a TFTP session, open 192.168.1.1, change to binary mode, and be ready to 'put' the file you downloaded.
- open a window with a continuous ping to 192.168.1.1
- connect a LAN port on the E3000 directly to your computer's ethernet port.
- with the router powered off, short pins 8 and 9 on the flash chip (I use a very small screwdriver).
- Holding the shorting-tool in place, turn on power to the router (I like the fact that the E3000 has a switch)
- Keep the chip shorted for a few seconds, then release the short.
- watch for the pings to respond with TTL 100.
- send the firmware with the put command from the TFTP client.
- the firmware transfer goes quickly, and the router will reboot automatically.
- Then wait... and wait... and wait some more until you see the ping return TTL 64.
- try to connect via LuCI or ssh.... should work!