That was indeed the battery causing all this, i think phoning app was also impacted with some outgoing calls not working (like if call ended in void), latelly.

Well, thank you for the hint, you saved my MX4 from unnecessary recycling !

Could be your battery failing.

Battery is definetly way too old, i'll try to find a replacement for it to test.

@domubpkm @Moem for now i'll use my spare N5 as my alarm clock, but i'll maybe get a real one yes.

@AppLee what's even weirder is now when i reboot, vibration works for sometime, and then stops working, and everytime it's when i'm writing something in morph (but probably just coincidency)

@Keneda Ubuntu Touch is an image, so theoretically copied at the same exact location in ROM. But there are mechanism to recover from bad blocks. It's too technical for me at this point.
But the temporary fix that you experienced doesn't match with the ROM idea ; either a reinstall won't change anything or the problems should be random...
Same for the RAM...

@MrT10001 is probably right.

Still it is hard to tell without probing the device and having it monitored...

new modern smartphone or classic clock radio ..

Or just a simple alarm clock. Those still exist.
Oh, there is another option: a suitable smart watch, such as a Pebble.

Now i wonder how can i know if memory is dying.

But if memory is dying, should changing channel (wich is basically reinstalling without wiping) work, or at least, shouldn't it reinstall on good blocks ?

Now i'm going to try changing channel again, after uninstalling all the apps i use very rarely.

If audio is fine in general but not for notifications, I bet it's the ROM that is corrupted where the notifications are handled.
Could be many things but an old eMMC with mileage after many updates and probable re-installation of the OS is something plausible.

Sorry you had a stressful morning.
On the bright side you got a couple hours of sleep that's good.

In my experience you shouldn't trust a phone and even less a smart one to wake you up.
The more simple the technology, the more reliable it is (or at least it's an easy fix or obvious when broken).

Now what you describe is strange.
But many things can explain it. My first guess will be a hardware issue, maybe the ROM or RAM getting old and with corrupted sectors.
If it is the RAM it can lead to many strange behavior that should change or be fixed with a simple reboot.
If it's the ROM then some apps will stop working properly until reinstalled.

I know your MX4 is getting old and things can go bad.

I wouldn't throw it away yet, but I'll consider frequent backup and for your alarm to use redundancy.

My guess is just a guess, but given that you had it working fine on OTA-22 it shouldn't be the soft except if you tinkered a bit too much to fix the vibration issue.

It remembers me a time when I was still fresh on Linux. I had my computer running with my distro for a while then I started noticing crashes with Firefox. It was more an more frequent.
I started to question the stability of the software then I noticed other software failing more and more.
After some time I had a kernel panic ; I panicked too but read the message and realized that my HDD was failing an reporting IO errors.
I analyzed my logs, backed up my files and reinstalled on a new disk ; no more crashes...
Software is tricky but hardware is no different and I found several time that bad contacts can make you loose your mind finding a non existing bug in your code.

This long rant is not very helpful but I hope you'll figure it out.
Keep monitoring your phone's behavior and it'll probably be clearer with time.

Is my device dying or so ?