T4.1 - How to properly power and boot without USB connected?

[jwhill]

I need to be able to power my Teensy 4.1 using Vin/GND without the USB serial and terminal connected. With Vin connected to 5v, the T4.1 powers ON, but will not boot on it's own unless I have the USB connected to my terminal application on my computer. I'm a little confused about this and would like to know the correct way to use the T4.1. Eventually, my T4.1 will reside on a PCB, in an enclosure located in a remote location with no supporting PC. Thanks for any guidance.

[BriComp]

Do you have something like this in your setup.

while (!Serial);

That will wait forever if USB not attached to PC.
You should use

while (!Serial && (millis() < 3000));

...which will wait for up to 3 seconds for USB connection before giving up and running rest of program.