Triggers do not work

The controller is probably not going to be easy to repair. I have had two of these 1537's that I got as a pair with different issues (bad LB and analog stick drift), so I combined these broken controllers into one. The analog stick issue ended up happening again on my second 1537 controller, so I ended up getting rid of it and looking for a newer controller. I don't recommend repairing this controller, since the controllers seem to have a high enough failure rate that issues with these controllers are common. This non-recommendation is because this specific controller is known for high failure rates of the analog sticks (this issue is known to cause analog stick drift), which becomes more of a problem as the controller ages. I even had to recover the firmware on one and did an exchange for the 1697 I use now, and it shows the same signs that always come up when they begin to fail.

I would recommend trying to find a 1697 controller if you are looking at used ones, but if you want a new one you will need to get the Model 1708 controller. Both the 1697 and 1708 seem to be far more reliable and aren't as troublesome (but they have their own set of issues with the plastic parts, which primarily are caused by a cheap LB/RB assembly).

With that being said, this is either an issue with the bottom motherboard or the controller frame. If you really want to repair this controller, I'd order both parts and not solder anything until you see the LT trigger works again.

If you replace the frame and it still happens, the bottom motherboard is bad. This exact issue has also happened on my 1537, and it was a frame problem for me.