I recently got my first Raspberry Pi (model 3 B+) plus a starter kit from Adafruit, and I have encountered my first challenge: boot the darn thing. The starter kit came with a micro SD with NOOBs installed, and without a way to check I will assume that it is current.
Problem: The power LED is blinking (solid 2sec, four 1Hz blinks, four 2Hz blinks, repeat), and the HDMI monitor shows the rainbow screen and a yellow lightning bolt in the upper right. I've looked into the "blinking power LED" issue and concluded that this is bad (yes, I've tried a different USB cable with the same effect). The ACT LED does nothing.
But beyond that, is there a specific meaning to the blinking power LED? That is, is the blinking pattern that I noticed significant or does it simply indicate "bad"?