Power Button not working after Battery Replacement

2015 15” Macbook Pro A1398

The battery was swelling, so I purchased the iFixit replacement battery kit, and enlisted a tech-savvy coworker to replace the battery.

Everything seems to have gone well, nothing seems to have broken in the process, everything seemed to be connected correctly.

Upon plugging in the computer to the MagSafe adapter it turned on immediately.

However, I found that the Caps Lock key light no longer illuminates (caps lock does work, just no light). More importantly, the Power button (part of the keyboard) no longer works at all.

I shut down the computer (from the Apple menu, did not force shut down) and I let it charge overnight as per the iFixit instructions. But as I said, the Power button does not seem to work at all anymore.

Unable to reset SMC because the power button does not do anything. No fans, no signs of life apart from the light on the magsafe adapter. As far as I can tell, after shutting down, the only way to get the machine to turn back on is by opening it up, unplugging the battery, plugging it back in, and then closing the case and attaching the MagSafe adapter, in which case it does immediately turn on. But, after it is shut down, there seems to be no other way to get it back on than repeating this procedure.

Need to figure out why the power button is not working (caps lock light is not critical for operation, but may be a clue). All other keys and keyboard backlight were functional.

Also I noticed that for a short time, all mouse clicks were interpreted as command clicks. Please help!