Sorry to jump on this old thread! I’m having exactly the same problem described above. I’m using a Pi Zero W, Samsung 8gb card and have the shim soldered to the gpio. Only other thing I have connected is a Microsoft combination keyboard & mouse. I’ve reflashed several times but always get the Failure to Authenticate message if I try to power up with an official Raspberry Pi power supply. It boots straight to the desktop fine if I connect the lipo battery on its own. If I then plug in the power supply after it’s booted it still shuts down when the battery runs low (thought that was worth a go!). I can do bits & pieces just running off the battery but it has a habit of shutting down just as things are getting interesting! Is there a simple way for me to remove the code I installed from the one-line installer to see if that does anything? Thanks!