Is your printer causing you problems? Book a Mila service partner so he can get the bottom of the error messages and fix them.
The black colour cartridge is probably empty. Check the fill levels.
Remove the USB cable and plug it into another USB socket. You may have to remove "unknown" from the device manager. If that doesn't help, you should completely uninstall and reinstall the printer.
Check all cable connections. In addition, check whether the network and WLAN are working properly. Check the error messages on the printer and work through them. You can also completely uninstall and reinstall the printer once.