Background
I have a "friend" who is currently employed at a job as a software developer. Unfortunately, this friend of mine isn't at all willing to look for solutions by themselves. They would rather contact me and describe their problem, and have me look into it.
I'm happy to help people out, but the problem with them is that since they have no motivation to learn by themselves, I have to start explaining from the basics, and then tell them about the solution. As you can tell, this is an extremely time consuming affair.
I've tried showing them how to Google for their problems, post questions on Stack Overflow, and refer to the developer documentation. Apparently, my advice has fallen on deaf ears. When they have a new problem and ask for help, and I repeat my advice, they follow up with "what should I Google", "I can't understand section X of the documentation", "can you help me find something better" and so on.
Sometimes they have a problem with the projects they are working on, and they ask for my help. According to them, these are "very small" problems which "shouldn't take up much of [my] time", and suffice to say they're not. Sometimes I'll develop a small demo of the thing they need, and this is followed by criticism such as "X doesn't work", "but this is not how it's implemented on website Y" and so on.
When I try to explain to them that it is just a demo, they offer access to the source code and ask me to look through it and adjust my solution accordingly. When I refuse it for obvious reasons, they keep pestering me with requests to improve upon the demo.
I've also tried refusing to help them by saying "no", but this leads them to start working out on a time on when we can discuss the issue.
Frustrated with the state of things, I've tried blocking them on social media, but when I do they'll usually try to contact me over another channel which cannot be easily blocked, such as through phone calls or voicemail.
Question
How can I get this "friend" to stop this behavior?
Ideally, I would like this person to become self-sufficient in this regard. However, any action that gets them to stop pestering me (I'm okay with them finding another person) is okay too.
I would prefer to resolve this in a way that avoids conflict.