BPI-M5 not powering on (no LEDs lit)

I inserted an SD card with Linux image and plugged in a monitor, keyboard and mouse. Then I tried plugging in my USB-C power supply ([email protected]). I was expecting to see some LEDs light up, but nothing happened. Do I have a faulty power socket or am I doing something wrong?

In case it helps: at one point, I accidentally plugged my HDMI cable into a Mac Mini instead of a monitor, and then I saw three lit LEDs on the Pi.