The Pine 100
I chose to breathe life back into a completely dead TRS-80 Model 100. Many years ago, my cockatoo had taken a liking to an exposed motherboard in my hobby room for the few minutes I was away from the room, and restoring that motherboard to a working state would have been way too much for me at the time. Instead I replaced the motherboard and turned the machine into something completely new.
Networking started as not-working
Banging my head against the wall for two days getting both Ethernet and WiFi to work!