My battery just died without any sign of being tired. No juice for oil warning nor neutral. 2 years old.
I bought my first AGM battery, a Westco, back in 2000. There was a lot of skepticism about them back them back then, but it was unfounded. Just getting rid of the vent tube was huge, was the slow self-discharge rate is a great benefit. I never got less than 8 years out of a Westco, the last one I bought is in the R100GS and has a 6/17 date on it. I never had an AGM fail suddenly like yours, they would just gradually get weaker. One of their attributes seemed to be reliability. Back in the old days with the flooded cell batteries sudden failure was the most common failure mode that I saw, plates being shorted out by crud at the bottom of the case. Battery quality has always varied, with the integrity of internal construction being a big variable. I figured it was only a matter of time when poor quality would catch up to AGMs like everything else. Purity of lead seems to be a big problem.
Sorry about the battery details. A good warning to all of you regarding too cheap batteries.
I found a thread about these cheap batteries.
Less lead inside but stronger acid solution to crank up the voltage. Shorter life though.
I read that the voltage after charging is 13.2V. The battery my friend brought for me to get my bike home was a cheap battery too. A few bucks more, GEL version.
I charged it over night, my CTEK charger show all leds lit so fully charged.
I measured 13.2V something so the info I read seems to match.
This type of batteries have tricked smart chargers as Ctek when constantly connected. The battery voltage is too high so the charger will not kick in. Battery will not give much current when it needs too.
Better to charge over night now and then when charger starts to feed ~14.5V until that stage is OK.
My blue K6 has also a cheap battery, 1 year old.
The new Global AGM I have ordered will go in there. (It has a low cost battery too. )
Cost more than double than my cheap failing one. My K6 battery cost 1/3.

My experience of short lived batteries since early 80's have been slower starter, need of kickstart. Not a situation when bike dies.
Getting stranded can cause a bad situation when it happens far away from home.
I have searched for a small plan b battery to plug in. All are rather bulky.
It must be a battery that can be charged by the bike. But very small risk it will happen again

I fetched the bad battery at my friends house today. Measured 12.67V. Connected the charger that quickly entered phase 4, ready to use.
Full after 15 minutes.
But battery had very low amps in it last time. A few shakes have changed it?
A charger with inbuilt 60A test load to simulate the starter would be fine.