Low and Intermediate wifi signal

So I got this phone from a friend who happened to break the display. This happened from him accidentally bending the phone. And you can tell by a small kink in the aluminum frame of the phone. Its kinked on the top part of the bottom volume button.

Anyway thats the extent of the damage to the phone. So I went and replaced the display and then sealed it back up. No problems at all. Besides the low wifi connectivity, which was a problem before the screen broke. So that rules my repair causing it.

So then I thought it would have to be the wifi antennae, or maybe the cable connector.

But I don't know for sure the last time I opened it up I saw some thing that looked wrong with the cable itself. As in it was stretched to much. And some of the wires in the sealed cable were showing through a little. So maybe its the cable. But how could it be if it was the cables fault. Then wouldn't just not work at all, if wires are exposed from the cable.

Thats what made me think it has to be the actual wifi module itself. So then I tested the 4g and cellular data and no problems. Compared to my other phone using the same sim card and location.

So with that all said I feel like it had to be just the wifi antennae but I want to make sure before I go ahead and buy either one. I feel as though there is someway to test either option more so that I know for sure it is one or the other. Because I don't want to buy both parts if it turns out I only need one.

Or can I just return a part if it turns out I don't need it after replacing say the antennae first and it solving the problem. Or does iFixit allow you to open the part and find out if you need it or not.

Thanks for any help you can offer!