This is the story of how I saved my NAS from not getting IP address. I have been using Iomega HMNHD-CE for 4 years. But it has been heavily modified tough. I replaced the 1 TB drive inside the NAS with a 3 TB disk. Moreover, instead of installing the stock firmware to the new disk, I installed OpenMediaVault. After transferring my data from the old drive, my NAS became better than ever.
The problem is, new firmware (by olderzeus) needs additional commands to successfully configure a network interface, which I forgot to add into
iface eth0 inet dhcp pre-up ifconfig eth0 up; ifconfig eth0 down; ifconfig eth0 hw ether 01:23:45:67:89:AB
Now my device was booting without obtaining an IP address, and there was no way to reach it. At least I thought so. Then, I realized the HMNHD-CE has a serial port. I needed a serial cable or another serial device to connect it. I didn’t have any cable, but I had a Raspberry Pi. Using three female-female jumper wires, I connected ground (GND), receive (Rx) and transmit (Tx) pins. The trick here is to connect Rx pin of the Raspberry Pi to Tx pin of the HMNHD-CE (and Tx of R-Pi to the Rx pin).
RaspberryPi <-> HMNHD-CE GPIO Pin 6 <-> J4 Pin 3 (GND) GPIO Pin 8 <-> J4 Pin 4 GPIO Pin 10 <-> J4 Pin 2
Using the Raspberry Pi, I opened a connection to serial console:
screen /dev/ttyAMA0 115200
After powering on the NAS, I was able to see what is on the screen of the device, which does not have any output port for graphics. It is like magic!