USB-C power not working

I have one of the early-ish 1.2A boards that I played with for just a little bit when I first got it, and then sat on my shelf for a while. Now I’ve dusted it off again and am having an issue.

When I plug in a USB-C power supply (65watt, supports 5V/3A and more USB PD 3.0), the red led flashes at a very regular rate, but I don’t see anything happening. I’ve got HDMI hooked up, USB keyboard, and ethernet. I’ve also got this usb serial cable hooked up, and don’t get any output (black, white, and green lines into pins 6, 8, 10.

However, when I unplug the USB power and plug the red wire into the 5v pin 4, the board starts up normally. I’m able to get into u-boot, the image from github, a debian SD card, etc. In this case, I get good ethernet, but no HDMI…guessing there might not be enough power coming down the 5v line for that?

Is there something I can do to get things started without using the 5v line from the serial cable?

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Check the schematics and confirm there are exactly two 5.1K resistors, one on each of cc1 and cc2 usb lines.