replaced battery now keypad doesnt work

[littlecub]

Have a 2019 pro and just replaced the battery. Turned it on to check that its charging.....Yes.
But now the keyboard doesnt want to work.Doesnt want to connect to the screen. Checked that all connectors were connected...check.
What connecter am I missing, could it be the trackpad cable as that was slightly underneath the edge of the middle battery. Just a little bit out of shape,only on the edge.Fixed that before I started screwing everything back down.
Can anyone help me fix my problem.
Thanks
littlecub

 

[benholt]

On the 2019 15" the keyboard and trackpad share the same T2-managed HID bus, so a single pinched or slightly-creased trackpad flex will kill both — which matches what you're seeing. Before you tear it apart again, disconnect the battery ribbon (the small vertical connector with the latch), leave it out for a full minute, then re-seat the trackpad ZIF connector and the keyboard flex separately. Even a hairline crease on the trackpad ribbon from being pinched under the middle cell can drop the I2C line enough that T2 refuses to bring up HID at boot. If it's still dead after a clean re-seat, the ribbon itself is likely the casualty — a replacement flex is around $25 and it's a 20-minute swap once you're already open.