I've been through this a few times, and it's normal. For me, step one is just acknowledging that it's normal and then forgiving myself for not being able to meet my own standards. It's taken me a solid six months to a year to really feel like I understand some codebases. Everyone struggles and goes through that period where they understand nothing.

I believe in you, and I think you can do it if you want to. Try breaking down your problem into small steps. Find a surface that you can attack to get more information from the system. If there are no useful error messages / logs coming from the system, maybe that's what you should start improving first.

I've also struggled with the burnout and social issues. That's life. I've struggled with not having many friends. I have maybe two friends right now, and we don't see each other often, because we're in different fields and we have very different schedules. Right now I'm filling my social needs by having a Slack channel that I've set up, and invited a couple of local developers to. It's slowly growing as more people are invited and we chat here and there throughout the day. It's like a tiny HN community - people who have similar work and interests. We give each other advice and often these people help me find a new approach to solve work problems.

I hope my thoughts are helpful, good luck.