How do I recover from my first (bad) presentation?

I think it is fairly common for everyone as a Software Engineer to have atleast a few bad days (and presentations) - that is part of being human in the process. Coming from someone who has had their fair share of awkward demos - One thing I have observed is that our reputation is fairly dynamic - so one bad presentation can be amply offset by a display of increased responsibility in work and taking initiatives to "present" and "demo" your work often - at places with lower stakes such as scrum calls, team meetings, etc.

Especially at the L3 level, people acknowledge that things (and the industry) are still fairly new for the person and one "bad" demo should not offset your chances for promotion, given it is an one off incident.

For me, I personally acknowledged to my manager in my 1:1s that I recognise I have not been demo-ing my work to the team often, and would proactively address the same to "learn" better. And if it helps, I have seen a lot more non-L3's (senior people) having a bad day with their demos once in a while, and I have observed that the audience in general, empathises with the speaker rather than holding it against them.

I don't know about your team, but I personally wouldn't be too hard on the literal junior engineer giving their first presentation. Public speaking is the #1 fear for most Americans (trends like this are also very common across the rest of the world), and engineers tend to be more introverted.

I imagine it didn't hurt you, but if you're really wondering, you should ask your manager about it in your next 1 on 1. Regardless of the outcome (so even if your presentation went well), you should talk to your manager about this to get feedback on your presentation skills.

My advice for the future is to go in more relaxed. Instead of thinking "If I fail this presentation, everything's going to be terrible", think "If I mess up, it's not a big deal and I'll learn from it". I know that it's easier said than done, but once you make this mindset shift, you'll go in with a more carefree attitude which will counterintuitively make you present better. More advice here:

• "How can I get more comfortable giving presentations in front of large groups?"
• "How to improve public speaking & your presentations?"

Lastly, this is much harder to convey with text, but a defensive communication technique I use all the time in scenarios like these is self-deprecation. So let's say I'm presenting something and my brain just completely blanks on a part. I will immediately say something like "Woops, I completely forgot what I was going to say here, give me a second" with a smile on my face. While people are amused at me being a derp, I can use that time to recover and get my brain to figure out what's next. I recommend going through my communication course if you haven't already: [Course] Effective Communication For Engineers