Hi Juleshoop97,
Thanks for contacting Apple Support Communities!
We understand that your iPhone won't power on therefore you're unable to see your iPhone when it's connected to your Mac, correct?
For your Mac to see that your iPhone is connected, your iPhone will need power. You can learn more here: If your computer doesn't recognize your iPhone, iPad, or iPod - Apple Support
Did you have iCloud Photos enabled on your iPhone? If so, then your photos will be stored in iCloud, so you won't need to transfer them to your Mac: Set up and use iCloud Photos - Apple Support
If you have a current backup of your iPhone, you can restore the backup to retrieve your photos once you have your iPhone repaired: Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
We hope this helps.
Cheers!