Rock Pi S unable to connect

I’m using the model with NAND, BT & Wi-Fi.
I’ve been trying to get it to work for several days, but I haven’t been able to SSH into it. I’ve installed the official Debian image on the built-in flash and even tried booting from a USB stick (yes, I zeroed flash like the wiki specified) but nothing works. It doesn’t show up on the network at all, not with Ethernet nor with Wi-Fi. adb also wasn’t able to detect it, even though rkdevtool was.

Does anyone know what the problem could be?

EDIT 2023-11-23 11:29: I’ve installed the Rock Pi Debian image on a SD card and wiped the built-in flash again. A new IP shows up on my network, but its hostname is not rockpis and SSH connections are refused. adb still doesn’t detect the device.

EDIT 2023-11-23 11:34: Unknown device is gone from network.

EDIT 2023-11-23 12:04: The device appeared again and responded to pings but disappeared when an SSH connection was attempted.

FINAL EDIT: The issue was the power supply. I was using power directly from the PC. This was not sufficient.

Please confirm whether the power supply is sufficient, the usb power of PC is not enough sometimes, you can use a DC Power Adapter instead