Took only about 2-3 hours, that is already amazing

I tested it when I got it, it booted using my ~1.5A supply into retropie to the controller setup, I shut it down here.
I completed the build and now it keeps restarting on me, just a few lines of init stuff, then fade to white and restart.
I tested the 2.5A original power supply (hat to solder a usb jack to it), same effect.
I also reflashed the image a few times, used a different SD card (16gb sandisc ultras that always worked) and same effect.
I have soldered nothing to the board, just plug and play as intended. Also I am not using a battery yet, still waiting for the one from the forum to be delivered. I am using kites image from github.
Did I break my new toy? And how? oO