Quoting from the GitHub's page:

The exploit is a race condition that requires precise timing and several other conditions to be met for it to trigger successfully. As such it can take a while for that to happen.

Which means that, sometimes, you run the code but it simply fails. When it happens, you can turn off the console and try again.

If i remember correctly, some memory address that needs to be overridden by the exploit is randomized on startup. The only way to find it is to just write to a random address, which often fails