Which ribbon did you use? Type-A or Type-B? Could you explain the steps you took to complete you mod?
I'm afraid I made a mistake in my post. This one is actually a 32 pin, and according to the Retro Modding website the 32 pin has no issues with either the brown or white ribbon. The 40 pin is the one where you have to be careful when selecting ribbon A or B. Sorry for the confusion.
As far as my method goes it was a bit messy since I've never done anything like this before. Never soldered and have shaky hands so was tough.
Originally I tried to solder the wire to DA1, and specifically on the Y-shaped area it was the left point of the Y on DA1. When powering up the console the light would flash green and then go out; screen would never power up. What seems to have happened was that I made a connection to both the left AND the right points on DA1, and guides say to be careful not to make a bridge between the left point on DA1 and and any other point. So I messed that up with too much solder.
I removed the solder as best I could and then, per one of the above poster's guides on Youtube, soldered it to the nearby capacitor, the closest one to DA1. This worked, and achieved the same result as what I'm having an issue with now, wherein the screen powers on but is overly bright and scan line-y. I assumed that if I removed this solder point as well and tried to fix up my DA1 point, which had too much solder left on it at that time, then the issue would be solved. So I removed the solder and wire from the capacitor and fixed up DA1 and soldered the wire to it again, correctly this time. The screen powered on fine but I did notice that there were scan lines at that point. The opening segment of Final Fantasy Tactics was super messed up, for example.
I had a ton of trouble getting everything to fit back into the case. It took hours of trouble shooting but what I discovered was that the ribbon Retro Modding had sent me wouldn't fit in the case because it had to fit between the motherboard and the back of the new screen. Upon tightening down all the screws multiple times and having it not power on anymore once the case was all put together, I came to the conclusion that the black foam pad that's on the back of the SP screens by default was the issue. It was too thick, so I removed it since I had seen that other modders no longer had it on the back of their screens, despite not mentioning that step in their actual mod guide.
So I'm thinking that one of the potential issues is that I damaged DA1 in the process of trying to solder it to that point originally. I don't have the actual tool needed to remove the soldering material when trying to fix bad soldered points, so I had to ultimately carefully pull it back off with the soldering iron tip. Perhaps that caused a problem? I have no real way of testing it.
I have some more parts for a 40 pin mod on the way, so I'll have another one to work on here in a few days, but the process of doing that one isn't going to help me troubleshoot what's wrong with this 32 pin mod I don't think.