Hate to have to ask this question since it's custom hardware that doesn't apply to everyone, but hoping someone can lead me in the right direction here.

I'm using a board with a MK66FX1M0VLQ18 (TQFP package) and MKL04 bootloader chip purchased from PJRC. I've gone this route before and had success, but this time, I can't get the USB to work correctly, and the LED never blinks. After holding the PROG pins low on startup, the power draw goes from 20 to 30mA and the USB device triggers in Windows that it's connected, but then it never gets the device descriptor and never loads the driver.

In addition, as I said, the LED never blinks.

The circuit I'm using is almost identical to the Teensy 3.6, with the exception that I'm trying to use the onboard regulator instead of external. The 5V I'm supplying is going into VREG_IN1, which appears to work correctly as I'm getting a nice steady 3.3V on the outputs. In addition, the USB device part of the circuit with the TPD3S014 is omitted. Everything else is identical

The main question, here's the crystal I'm using:

https://lcsc.com/product-detail/SMD-...SI_C13738.html

Now it says it's 16MHz with 9pF load capacity, but the datasheet doesn't specify, and I can't find a better datasheet anywhere on the internet, so just trusting the data on the page.

However, I am seeing the crystal startup after releasing the PROG switch. My scope is not great, but there's definitely a nice sine wave looking oscillator at 16MHz, whether it's perfectly 16.000 I don't know for sure with the tools I have.

My gut says the crystal is not a 9pF load crystal and my 16 is off.

Main question to move me along:

If the USB fails on startup with the default program loaded from the MKL04 on first startup, will the LED blink? If not... what would cause the LED to not blink. Or maybe I don't understand how the MKKL04 actually works, maybe there's no program on there yet at all? I have checked the pin with a scope as well, no signal on pin 110 (PTC5).

Also, I've gone through all the troubleshooting and forum posts I can find hoping not to have to post another one of these. So to get ahead of some questions:

PTA4 is floating, double checked that.

There is a ground plane under the crystal, it's a 4 layer board, crystal is very close to the pins with a small ground pool around them connected only to the ground pin nearby, which is connected to the main ground plane.

Having said that, I still think it's the crystal somehow, but hopefully the LED not blinking is enough of a clue for someone more informed. Thank you so much in advance!