Teensy 3.1: usb not found (was working) ... related to pins?

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Hi all,

I have a Teensy 3.1 with a SparkFun TeensyView on it. I've successfully programmed a couple times before.

But now I find that when I plug it in to my Mac's USB port, Arduino 1.8.7 is no longer detecting it as a USB serial device.

The thing that's changed is that I hooked up a 4x6 keypad matrix to pins 0-4, 6-9 and 12.(The TeensyView is using pins 5,10,11,13 & 15.)

(I should have breadboarded this first, but I was in a hurry and thought "what could possibly happen?")

My question is: could these new pin hookups have something to do with the Teensy not being detected? Are there pins shared with the USB port, for instance?

Any other theories would also be much appreciated. Thanks!

Is the Teensy running on starting up - and after? If the code goes into the weeds the USB will not be found. Or if the Tools select when built somehow doesn't include Serial?

But as noted in post #2 - USB is native and wired to the USB connector - it does not share pins with Serial1 port - or other.
Perhaps one or more pins isn't connected as intended, maybe shorting out the 3.3V power so the Teensy can't run?

That was my thought wanting to know: "Is the Teensy running on starting up - and after? " If not failing to run the added software - it could be bad connect - or the design of the matrix …

The TeensyView is on pin 13 - so if working that will blink and ideally have a working display - if not then pause in setup for some seconds with pin 13 as output before .begin of the display and blink the LED.
HA! Okay, never mind, problem solved.

One other thing changed: I accidentally grabbed one of these stupid power-only USB cables!

New cable, no problem.

Funny, sometimes I need to ask someone else before my own brain will keep working on the problem. So ... thanks!

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