Is it too late to break into Investment Banking?

I'm assuming that you don't have a bachelor's degree by the way you phrased that. If that's true then you don't need a finance degree. Banks train their interns and analysts on what they need to learn. You just need a baseline intelligence that proves you're teachable and you can display that by your school, GPA, standardized test scores, knowledge of technicals, and achievements. You also need to convince them that you have some type of passion and interest in finance other than the money you can make at a bank. A finance degree is one way to show that but it isn't the only way. However, a rule of thumb is your major matters less and less the more selective your university is. Like if you go to Harvard you can take philosophy. If you go to a complete non-target state school then you should probably aim for something more STEM or finance related.

Your age won't work against you too much. You wouldn't be the first late 20s early 30s to get an entry position at a bank. However, you will be around kids in their early 20s and some of them will be your superior, that's hard for some people to tolerate. If you don't have a bachelor's then you would be around 30+ by the time you're an analyst. People are usually VPs by 30 so you'll have people your age treating you like you're in your early 20s, again, some people can't handle that. You'll have to swallow your pride a little, but people have done it.

If you have a bachelor's then an MBA from a top school is the way to go, and you can recruit as an associate. A lot of the same still applies, you'll be older for your position and a lot of analysts will know more about the work than you despite the position. You'll be like 30 getting attitude from some 23 year old kid who you will want to smack, but that's life.