Keyboard and Touchpad Not Working After Battery and TP Replacement

Early 2015 MacBook Pro 13”

Here’s what’s happened so far:

1. Replaced a dead battery. Forgot the flip up the tab on the touchpad (TP) cable connector on removal. Reinstalled everything.
2. Touchpad and keyboard didn’t work in MacOS. Touchpad doesn’t respond to anything. No keyboard keys, caps lock, etc work in MacOS. Worked with external USB KB and mouse. Built-in power key powers laptop on. System info doesn’t recognize the touchpad.
3. At one point also had a power issue where the CAPS Lock key was staying lit up. SMC reset using built-in keyboard fixed this.
4. Note: In general from here on out, the SMC reset from the built-in keyboard seems to work because it won’t boot while the keys are held down.
5. Ordered a new touchpad and touchpad cable. Replaced. Same KB + TP behavior.
6. Tried more SMC resets and NVRAM resets. Tried NVRAM reset from command prompt. Tried keyboard SMC and NVRAM resets from a wired keyboard too.
7. Replaced the TP cable again. This time I didn’t bend it at all as this was my suspicion. Tried booting laptop on its side so cable could stick out. All the same behaviors.
8. I’ve also tried rebooting from System Information Hard Disk and just holding down power for 10 seconds to turn off.

At this point it really doesn’t make sense to me that the brand new cable wouldn’t work unbent with the brand new touchpad. The connector at the motherboard looks fine. As far as I can tell the SMC reset is working when done with the built-in keyboard. It almost seems like some kind of software or system issue. I’m lost but feel like I’m 1 step away from getting it back to working.

Images of original touchpad. Original cable top, 1st replacement middle, 2nd replacement bottom. All images of the same parts. This touchpad was removed and replaced.