You've certainly tested up and down, and the only thing to add from my own experience is to turn off the keyboard (two quick clicks of its side button or one long press of more than 10 seconds).
The reason I suggest this is because if I shut down my PP Beta/kb and don't turn off the kb, I get a big power drain by the next day.
If that doesn't help, you could try (if you haven't already) Megi's custom kb firmware: https://xnux.eu/log/078.html to help matters along.
The reason I suggest this is because if I shut down my PP Beta/kb and don't turn off the kb, I get a big power drain by the next day.
If that doesn't help, you could try (if you haven't already) Megi's custom kb firmware: https://xnux.eu/log/078.html to help matters along.