Need help setting up NRF52 for serial connection to IDE

I'd like to use Web Serial (not Web Bluetooth) for IDE on an NRF52 breakout board.. Here are lines from the board file:

info = {
 'name' : "C20 smartwatch",
 'boardname' : 'C20X', 
 #'default_console' : "EV_BLUETOOTH",
 'default_console' : "EV_SERIAL1",
 'default_console_tx' : "D5",
 'default_console_rx' : "D7",
 'default_console_baudrate' : "38400",
...

The build works (I still have Bluetooth in the libraries and my test board can connect to the IDE that way). I'm using a CP2102 to connect with TXD going to D7, RXD to D5 (and I've tried it reversed as well). Wiring to D7/D5 is solid. I've set the IDE to use the same baudrate for Serial. When I try to use Web Serial, I get:

Unable to retrieve board information. Connection error?

What am I missing?