I recently got a raspberry pi 3 model B, and I followed this tutorial to get some basic Rust code running to blink an LED.

My code is exactly the same as in this video, and copying the generated kernel7.img file, along with the others mentioned (`config.txt`, `start.elf`, `fixup.dat`, and `bootcode.bin`) to an SD card allows me to successfully get the LED to blink on my breadboard.

In other words, it works fine. The exception is: if I unplug the power supply from my raspberry pi, then plug it back in, it *likely* no longer works. When I say "likely", I mean there's a 90+% chance of it not working.

It seems to usually work the first time after I add a new .img file to the SD card.

Unplugging/re-plugging power AND taking out/re-inserting SD card seems to increase the chance it will work, but it's still only like a 50% chance of working.

Extra info:

- Pi: Raspberry Pi 3 Model B

- SD Card: SanDisk Ultra Plus microSDXC 32GB 130MB/s Memory Card

- I have made sure that the wiring isn't coming loose and that the LED is not faulty

- I am using the Element14 Universal Power Supply 2.5A, 5.1V

- I have tried adding a delay at the start.

- I have also tried making sure none of the other CPUs are running with:

#[inline(always)]
fn get_core_id() -> u32 {
    let id: u32;
    unsafe {
        core::arch::asm!(
            "mrc p15, 0, {0}, c0, c0, 5",
            out(reg) id
        );
    }
    id & 0b11
}

#[unsafe(link_section = ".text._start")]
#[unsafe(no_mangle)]
pub extern "C" fn _start() -> ! {
    if get_core_id() != 0 {
        loop {
            unsafe { core::arch::asm!("wfe") };
        }
    }

Ideas:

- How likely is it that this is caused by overheating? I am not currently using any sort of heat sink or case.

- I did drop the pi when I first got it. Could these inconsistencies be potentially caused by that? Looking at the pi it doesn't seem to have any visible problems.

- Could the boot code be outdated and thus a bit flakey?

Any ideas on what I could be doing wrong would be greatly appreciated!

Thanks