it closed itself with no error at all.
Did you start it from console? If not, try it: leave the console open to see if it outputs anything there when it closes.
When running from the console, sometimes when the program crashes or closes on its own, some error messages are displayed directly in the terminal. The terminal error board helps determine which location is causing the problem. So, once the console is open, launch Bitcoin Knots. If any (output/error) code appears, debugging will be much easier. Also, be sure to check the (debug.log file).