Raspberry pi 4 shows solid red light

Question

My raspberry pi 4 is showing a solid red light, the green light stops blinking shortly after I power on. Everything was working fine up until last night, I have the raspberry pi power adapter, 64GB memory card and was running the Raspbian image downloaded by the Raspberry pi imager tool. Last night I changed the Wi fi network it uses, I was interfacing with the pi via an ethernet cable directly from my laptop. I came back later in the evening and nothing was working, I have re-imaged the card, and tried a both SSH and VNC, but nothing is accepting the connection, the only thing that is responding is the ping on the address of that network interface. I was wondering does anybody have any idea what happened here, and is there any way to fix it? Could something have happened during shutdown that caused something to get corrupted? The only major change I made was to change the WiFi network, but even now after a full re-image nothing is working. Any help greatly appreciated.

Answer 1

In answer to your comment "how could this have happened" powering off without shutting down the Pi first can corrupt the SD card sometimes to the point it's no longer usable.

Answer 2

Isolate the Pi issues by supplying a known good SD with a fresh install Raspbian OS with your wpa_supplicant.conf adjusted to your network AP settings, and copy that folder to the SD's /boot folder. As stated, the ping response is software from the Pi responding to the ping request.

If you are using ethernet as you say, then try pluggin it into your router.

So if you get a ping back then more than likely your Pi is alive. Try putting Pi on your network, not direct to the Laptop. You might have different IP address because of that.

If you setup the wpa_supplicant.conf file:

    ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
    update_config=1
    country=GB

    network={
             ssid="IoT-Lab"
             psk="12323233"
             key_mgmt=WPA-PSK
    }


    network={
            ssid="Node1"
            wep_key0="6172736869"
            #wep_key0=6172736869
            key_mgmt=NONE
    } 

source: https://stackoverflow.com/questions/46276408/how-to-connect-raspberry-to-wep-encrypted-and-dhcp-enabled-ad-hoc-network

Use this as a template, so change according to your wifi setup, and save the file to your /boot folder on the SD... On next boot, your Pi will save these settings and connect via wifi if you have it.

***Please note that some Pi models come with low amounts of RAM memory, and if you max this out, your Pi can become unresponsive.