Working in a startup is very different from working in a corporation, as you found out. As a single developer, you can not change the big corporation in its ways, how ever wrong they are. I think you have three options:

1) keep trying - and burn out in a few years

2) Adjust to the corporate life style stop caring, make do, and find something else important in your life. A hobby, a side project, something to burn for.

3) Get the fuck out of there, find (or start) another small company where you can feel at home and do meaningful work.

Good luck, what ever you choose!