I’ve been using a 3B+ headless for several months. Yesterday I rebooted like I normally do using
sudo shutdown -r now. It shut down, but wouldn’t boot up again. I figured I had done something to the SD, so I formatted a brand new SD card with Raspbian and tried to boot again.
Now, my Pi boots up just fine — if I connect HDMI I can see that it boots to the Raspbian desktop. However, the green activity LED on the Pi never lights at all. Moreover, with ethernet connected, the Pi never connects to the network, and neither of ethernet LEDs ever light.
First thing I thought to check was the power supply. It’s the same 5V supply I’ve been using for months, and I tested voltage across the test pads at about 5.2V. I’ve tried two different freshly-imaged SD cards, and two different ethernet cables. What’s going on with my Pi?