Chosen Solution
I was using my computer, took a break to do something else, and went to open it back up and suddenly the trackpad was very delayed and and keyboard wasn’t working so I reset it (using the power button) and now the trackpads not working at all along with the keyboard I tried to troubleshoot it and attempted to do a SMC reset but any time I click/hold the power button it turns on right away and I can’t go through all of the steps for that. the thing is is that whenever I try to move the trackpad or push a key the blinker for the type indication delays as if it’s taking a second to process something and then doesn’t (other wise it blinks at a regular consistent speed). Also after a bit it’ll tell me there’s no keyboard connected and nothing happens. I don’t think it’s directly related but I’m gonna mention it just in case it could be. A week ago I did replace the battery using a kit I bought on here. Expect the thing is is I haven’t had any issue relating to the keyboard or the mouse since the issue earlier today already mentioned so I don’t think it has anything to do with that. Seen below is photo of battery data but I’m pretty sure that’s installed fine I just mentioned it as a passable cause.
Update (05/19/2020) This image came up and from what I got from it is that I need to bring it to apple to fix stuff. Slightly related to this point will apple take my MacBook if I tried to fix it on my own because as I said I did replace the battery and I know some companies say you’re on your own after that
Try getting the trackpad cable replaced. The part is relatively cheap and easy to replace. That cable is very common to go bad on any MacBook Pro model in 2015 due to the design where the cable can easily get damaged by debris due to the placement of it being on top of the battery and right under the removable bottom cover. The trackpad cable has an I2C data line which has the data signal from the keyboard going to the trackpad first which goes through that cable, then back to the main board. When that line is cut both the trackpad and keyboard (sometimes it’s either or both) will not work. And yes those errors are most likely related to trackpad cable too. Don’t take it to apple yet until you’ve tried replacing the trackpad cable.
