[Bluescreen]

As I said, firmware is 5.8.9.2, sadly. I don't know how to downgrade, the usual way via "update my kindle" does not work anymore with that version.

I now created a little test script to see the powerd events which are happening.
The script puts the current time plus 15 minutes into the wakeupalarm and then waits for all events from powerd.

#!/bin/sh

ENDWAIT=$(( `date +%s` + 900 ))

echo Wakeup time : `date -d @$ENDWAIT`
echo Current time: `date`

echo 0 > /sys/class/rtc/rtc0/wakealarm
echo $ENDWAIT > /sys/class/rtc/rtc0/wakealarm

lipc-wait-event -mt com.lab126.powerd '*'

Starting point was Kindles normal operation mode.
As you can see in the following log, all the expected events came but the wakeup event.

Wakeup time : Fri Jun 30 19:14:38 EEST 2017
Current time: Fri Jun 30 18:59:38 EEST 2017
[19:04:29.706631] goingToScreenSaver 3
[19:05:29.811153] readyToSuspend 10
[19:05:34.813016] readyToSuspend 8
[19:05:39.818784] readyToSuspend 7
[19:05:59.939158] readyToSuspend 7
[19:06:04.910156] readyToSuspend 6
[19:06:09.949382] readyToSuspend 2
[19:06:14.926352] readyToSuspend 1
[19:06:23.667195] suspending "mem"

I sampled the output at 19:25. After pressing the power button to wake up Kindle manually, this output happens:

[19:25:45.384165] wakeupFromSuspend 1160
[19:25:45.392901] resuming
[19:25:45.411959] t1TimerReset
[19:25:45.470198] outOfScreenSaver 1

So I think all the event stuff is working as intended, only the wakeup timer does not work.