Pro Controller Seemingly Dead

Hello everyone, this is my first time here so please forgive me for any errors. Recently I noticed that my pro controller has been acting up with the minus button not working, and so I wanted to investigate what is wrong with it. Upon taking the board out with those buttons and testing, when putting it back together I noticed that the controller would not turn on unless it was plugged into a usb-c cable, which was odd. During this stage, when plugging it in it would give a quick orange light flash, indicating that it was charging, then immediately turn off. The controller could still connect to the switch while plugged in. Somehow, someway after that the controller would not turn on at all, even when plugged in. This is definitely something I could have caused, but I have no clue what I could have done that caused this.

I am lucky to have a second pro controller I can use to test the components, so here is what I was able to figure out:

• The battery from the broken pro controller still works
• The face buttons and ribbon cable are still working, but are not necessary for the controller to turn on.

I don’t know if I can edit this post but if I can I will write down more here as I figure out what is wrong.

The only thing I can think of is that something on the board shorted as I was taking it apart, or that the rumble motors are required to be connected for the controller to turn on, since right now they are disconnected. I saw in another thread to use a multimeter to test some of the components, I’m pretty inexperienced with one so if that is a test I need to do it would help if I could have layman’s directions. I really don’t know what can be causing this and I hope I can get some guidance to get it back up and running.