I have a strange problem with a Pi 4.
I have my Raspberry Pi 4 powered by an external alimentation 5V 2 A, there are two USB devices connected (an Arduino Mega and the touch USB for the display) and an HDMI display.
When I am trying to boot from an SD card with this configuration, it won't boot. But when I unplug a USB device it boots. I can then reconnect the USB device and it works perfectly.
I don't think it is a power supply issue because it works after I unplug and plug again...
Does someone know why this happens?