Pixel 3 stuck in Fastboot mode with "no valid slot to boot" when trying to install factory image I was trying to install the factory software image from https://developers.google.com/android/images#blueline on my Pixel 3. I downloaded the image as well as the platform-tools with adb and fastboot. 

After plugging in my phone, I ran "adb reboot bootloader" which put me into Fastboot mode. After this I tried to run the flash-all.bat file, but it was just stuck on the "waiting for devices" prompt. I'm not sure what I did at this point, but I must have really messed up the phone, because now I can't even boot from Fastboot, where clicking "Start" just puts me back in fastboot with the reason "no valid slot to boot." Any idea how I can get my phone working again?

I tried putting my phone in recovery mode, but I just got "error booting boot.img"
In this state I was just able to run "flash-all.bat" - which let me load. Not sure why it wasn't letting before.