2015 MacBook Pro keyboard & trackpad not working

I was sharing my recent experience is hopes of encouraging you, and affirming those cables are nasty, and that the one that gets inserted below-and-behind the trackpad is the nastiest.

I recommend you try my technique of removing the trackpad and re-installing that end of that cable with lots of room to move, as I did. Maybe your luck will change.

Also, try Option Booting the laptop by holding down the Option key immediately after hearing the startup chime. Let the computer sit at the Apple boot picker menu. Does the Trackpad or Keyboard work here?

Try running the Apple Diagnostics to see if any hardware issues are detected. I doubt this will give us any useful information, but it doesn't hurt to try.

Use an external USB wired keyboard to Option Boot & access the diagnostics if necessary.

You didn't mention the exact model. With the 15" model it requires removing all of the electronics to replace the battery while the 13" model I believe can have the battery replaced without removing anything (or just lifting a portion of the MLB....it has been a while since I last worked on a 2015 model).

Make sure the Trackpad Cable is fully seated on both ends and the Keyboard connector is fully seated as well. It can be a bit tricky with the keyboard connector if it is one of the ribbon flex cables. I like to put a piece of tape on the cable in order to pull it into the connector before securing the latch (just be careful removing the tape afterwards since you may pull the cable from the connector even with it latch engaged).

Chances are you accidentally damaged something if it was working fine before the battery replacement and assuming the replacement Trackpad Flex Cable is actually good. Since the Trackpad resides beneath the battery, I could see damaging the Trackpad as you tried to remove the old battery (either from the adhesive softener or from the pry tool to separate the battery).

If the Trackpad Cable doesn't solve the problem then it means either the Trackpad itself or the Logic Board is bad, or the Keyboard cable/connector is damaged.

Inspect each cable & connector carefully.

I second HWTech statement about how diabolical those tiny cables are. I was completely unable to re-connect the one that goes right against the trackpad. There wasn't enough room to push the cable-end into the connector.

I had to remove both ends of the cable and the trackpad, connect the cable-end that goes right against the trackpad, then re-install the trackpad, then connect the farther-away cable-end that has more free space around it. That was NOT fun.

markoid63 wrote:

I just changed the battery on my 2015 MacBook Pro, everything seemed to go well. I charged it up no problem, but the trackpad and keyboard aren’t working. I opened it up again, everything looked fine. Tried again, still not working. Did lots of research, suggestion was to put a new trackpad cable in, which I did, but no difference. I’ve double and triple checked all connections but I’m frustrated and scratching my head as to what has gone wrong. I can plug a keyboard and mouse into it and it works fine, but not an ideal solution. If anyone can throw some ideas my way I’d appreciate it. I know it’s an older MacBook but it still worked well, I just can’t afford to go to the Apple Store and spend more money on it.

you can try both—

resetting the System Management Controller Reset the SMC of your Mac - Apple Support

resetting NVRAM/PRAM Reset NVRAM on your Mac - Apple Support

The Alt/Option key is the one most transposed on Windows keyboards.

Pretend the Windows keyboard has no labels on the keys, and try holding the key in the same position as Alt/Option on the Mac keyboard.