Is there any known issue with the Pi 3 B+ and the ArPicade firmware..??
The reason I ask is I have bought two new 3 B+ and both refuse to boot with a vanilla version of the image (V3.7). On both units all I get is the lightning bolt on (a black) screen, no boot and the power LED on the Pi flashing (four slow, four fast flashes).
Everything I've researched points to the power supply not being able to supply the current, but given I'm running an Arcade style power supply (+5v @ 5a) which measures 5.1V at the Pi, I can't see that being the issue. I've tried another USB power supply (2.5A) and also directly wiring the +5V from the arcade power supply to the Pi (PP2 and PP5) - both no go.
The same firmware has been tried on a Model 1 and Model 2 successfully (all clean installs of V3.7)