Really well designed boss encounter! I love the heat/cooldown mechanic and the way it effects both you and the boss. Making it a matter of survival and outlasting each other was a nice move. I felt like I was witnessing a match from robot wars at one point haha! The art work is really nice and everything felt nicely balanced. I didn't find myself using the shield much, but simply learning the boss patterns and how to move around it was a really fun experience. I saw you mentioned your small time frame to get this done so it's a very impressive turn around. If you had a bit more time, some music and sounds would have enhanced the experience even more, but to produce this in the time you had was great!
Nice work :)