budget mirrorless camera

[yoursoawsome]

hello,

Im a 15 year old film maker looking for a camera. I do have a pentax q7, but I am wanting to return it so i can get a new camera. The pentax is just fine until it recently started to shut down in the middle of shoots. I also don't really like the insane 4.7 crop factor. Because of this, it's pretty hard to use other lenses with larger focal lengths without being a mile away from your subject.

All I'm looking for is a camera under $350 and is good to shoot video with and with a large sensor size so crop factor can become less of a problem. Whats a good universal lens mount? is the 4/3 universal? What's the difference between 4/3 and micro 4/3. Nice additions, but not necessary are an adjustable screen, hotshoe, and audio input.

thanks