The error message indicates that the public signature key with id 40976EAF437D05B5 of a repository is missed. I don't know where to get the public key but because an Ubuntu repository is missing it, it is possible to get the key from the Ubuntu keyserver. Try to get and import it with:
rpi ~$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys ...
That looks like one of the inductors - if you get yourself a schematic there are two - L1 and L2 that are 4.7uH, both used to provide the internal voltage rails, 3.3V and 1.8V from the 5V supply so unless you are able to refit a new one I afraid that it is probably broken.
OP said, "power it with a 5V, 2 A supply. I don't use any peripherals with it."
OP also said, "the (sense) hat on top of it lit up too" (emphasis mine)
Raspberry Pi docs said:
Recommended PSU current capacity for Pi 3B+: 2.5A
And so you'll have to excuse those of us who wonder if you've a) not done your homework, and b) wandered in with ...
If you REALLY want an Answer - you CAN'T "fix it" because this is how virtual network interfaces work.
If you read the documentation you will discover that you can only define a virtual network interfaces if the interface exists, which yours WON'T if not connected to a DHCP server.
There is also NO POINT in attempting to define a netmask (or CIDR ...
The "the given serial cable" is a bog standard miniUSB to USB-A cable.
This information belongs in your Question - as does ALL technical detail.
The reference to "Serial Cable" is misleading the cable is USB; the serial interface is on the Arduino - no additional serial interface is needed. (It is technically possible to connect the Pi ...
It probably booted ... but not with WiFi and ssh enabled.
The formatting on your post makes it look like you may have missed some info in your /boot/wpa_supplicant.conf
It should resemble this:
country=<Insert 2 letter ISO 3166-1 country code here>
I'd add a comment but I don't have enough rep yet - We need to see the schematic of the remote you're trying to connect it to before we can answer.
Edit: Scratch that I think I see the issue:
Your circuit does not match your circuit diagram.
You've got pins 1 and 3 mixed up on your transistor.
You also do not seem to have connected the Pi and remote to a ...
You used make to create gettingstarted so I assume it is compiled to an executable file and not only a script for an interpreter (bash, python, etc.). Having this you are able to use the setuid or setgid flags on the file. This flags on file permission are used to execute the file with the rights of its owner or group and not with the permission of the ...
Possibly the driver you are using is not the correct one for the screen, I had the same problem and changing the driver from SSD1306 to SH1106, and it worked correctly.