Hello, could really use anyone's help if they have it .

A friend of mine has a CSE, and he says that the "buttons don't work unless you press hard enough." But this wasn't the case because if you hold down the button long enough, it will register the press. So I came to the conclusion that the I/O port was the issue. So, I read this post and went through the work to find a Torx-6 screwdriver and de-soldered the I/O port in hopes that the calculator would return to normal state. However, after removing the port the calculator is still taking very long to respond to a button press . Now I'm curious as to what is causing the calculator to do this.

Any advice right now would be such a help. Thanks so much for any help.

If it's just generally slow (not so incredibly slow that it takes ages to enter something in, but relatively slow as in if you type too fast some keys may not register) Then that's just the CSE being itself. If you did not know, the ti-84 plus CSE is the slowest calculator in a very long time (I don't know how really old models like the ti-80 perform, but from what I've seen, it is noticeably slower than the last few monochrome models) This slowness is due to the calculator having the same 15 mHz processor as the older models, but bearing a color screen that has something like 3 times as many pixels.
As for removing the I/O port, I would strongly advise against that, I've never heard of that fixing any issues, and you probably risk damaging the calculator.
From what I'm seeing however, this is more than the calculator being a little slow. Do you know if any liquids have been spilled on the keyboard? I know the CSE has a removable faceplate which also involves little holes that poke directly into the case which serve as a great weakness (stuff falls in then sounds like something broke off and is moving around freely inside the case, but also easier for liquids to sneak in) If a spill is the culprit, then although this is definitely not guaranteed to work since we don't know the exact extent of the damage, you will want to unplug the battery and carefully clean the board and key mat with a bit of isopropyl alcohol and a soft brush (the standard procedure for cleaning spills on electronics). Note that the keys are not stuck onto the rubber mat, so you can take them off and clean them if necessary.

I am aware that the cse is slow, but to register a button, you have to press and hold the button for 4-5 seconds, where then the calculator recognises it. And you can't press (and hold) the same button twice in a row. I can (slowly) pull up a menu, but the items and text loads just as fast as my CE. No spills or no liquids. No sticky keys, circuit board feels smooth and fine. This is a new calculator; bought this September for school. Also I'm not too worried about removing the I/O port since I know it wouldn't be used.

Check for blown capacitors on the board.

I checked the entire board; nothing out of the ordinary

If you bought it less than a year ago and have the proof of purchase, then the unit is under warranty. Consider calling TI and have them either fix it over the phone or replace it.