HP Pro x2 612 - power keyboard stopped working

[regexaurus]

A few weeks ago, I updated the BIOS (to 1.36 Rev. A) of an HP Pro x2 612 tablet with the power keyboard/dock. The update was successful and if I recall correctly, also flashed the power keyboard. This may be completely unrelated to the update, but this past weekend, the power keyboard stopped working. The tablet still works fine, but does not detect the power keyboard when docked and the power keyboard doesn't seem to charge. I had access to another power keyboard and the tablet works fine with that. I also tried a different tablet with the problem power keyboard, but that tablet didn't detect the power keyboard either. It seems to be "dead."

Are there any recommended troubleshooting steps for the power keyboard before I dispose/recycle? I would like to at least make a reasonable effort to repair/recover the power keyboard if there is something I can do. I'm not opposed to removing screws, etc.

Thank you!

[regexaurus]

So I "cracked open" the power keyboard. Holy screws, Batman! I tore it down to the logic board...had both boards removed from the bezel/case. I wasn't sure what I was looking for--a blown through-hole electrolytic capacitor (there are none)? For kicks, with the logic board removed from everything else, I connected the power adapter. The power LED came on; it wasn't doing that at all when I had the problem. I re-assembled everything except the bottom cover and left the battery disconnected from the logic board. Plugged it in again and this time connected a tablet. The tablet detected the keyboard base! Undocked the tablet and disconnected the keyboard/dock from power, connected the battery and completed re-assembly. Re-connected to power and confirmed the tablet still detected the power keyboard.

Odd to say the least.