iPhone Blinking in Finder

Hello and welcome to Apple Support Communities, Kettleer.

If I understand your post correctly, you're not able to select Trust when connecting your iPhone to your Mac. I’d like to help.

Follow the steps in this article:

If your computer doesn't recognize your iPhone, iPad, or iPod

Let us know if that resolves this issue for you. 

Thanks for using the Apple Support Communities. Take care.

Hello Kettleer.

It sounds like there could be a problem with the USB port. Does this happen when you use another USB port?

If it happens with multiple ports I'd recommend contacting Apple Support directly. You can do that here:

Contact Apple Support

Cheers.

Hello Kettleer.

I'd recommend this reset:

Reset NVRAM or PRAM on your Mac

If this issue continues after the reset, let's do some testing to narrow down the issue.

Safe mode will tell us if the issue is related to a startup item or plugins, and sometimes corrects the issue. This article will tell you how: How to use safe mode on your Mac

If everything is working correctly in safe mode, but is not working when you get back to your user account, please check the section titled "If the issue doesn't continue in safe mode" for the next troubleshooting steps.

If the issue continues while in safe mode, a test user will let us know if the issue is isolated to your account, or system wide: How to test an issue in another user account on your Mac. If the issue happens in the test user also, then please check the section titled "If the issue happens in the other account."

Cheers.

Hello Kettleer.

At this point, we'd recommend contacting Apple Support directly. You can do that here:

Contact Apple Support

Cheers.