Dell XPS12 doesn't work with charged battery

[presiden]

Prehistory: XPS12 was placed on the table in my office, and I was simply browsing, on battery power it allowed me 4+ hours of ontime. Battery was at around 85%, when suddenly it just clicked and immediately went off.
Sure, I tried to start it again. What happens: after pressing the power button the notebook starts to load, but after random time from 1 to 10-15s it "clicks" and dies. Tried that a dozen times.
After coming back home I connected the charger - and notebook started as intended. Then I shut it down, disconnected the power cable and tried to start - same "click and off". After connecting the notebook to the power adapter it started again properly, and after I just disconnected the cable - notebook clicked and died.
So, at the moment: battery is OK (BIOS writes it's working normally) and fully charged, but the notebook refuses to start or stay on. And it happened without any drops, kicks or any other physical actions, notebook was peacefully resting on the table.
At the same time, it works with the external power connected. We disconnect the cable - a second or few, and it dies.
As I know, the battery in my notebook is non-removable, so cannot make any experiments with it.
Any suggestions from respectable gurus what should I do? The additional problem is I'm in Thailand, so bringing the notebook to local service center isn't an option.
Edit: I installed Aida64 and gathered some info. Battery wear is 11%. Battery voltage with AC adapter conected was 8,1V. Then I unplugged the adaptor - about 6-10s it was showing the same voltage (very slight deviation), then notebook died again. If battery would have some bad cell in it, probably the voltage would drop immediately after AC adapter disconnect?

 

[Laptop_Nerd]

Hi,

It seems like that the battery of your laptop is faulty already and needs to be changed already. Since the laptop will stay on with the AC adapter connect that only means that the AC adapter is working and it's just the battery that is not. One more test you can do is to remove the battery off the laptop then connect it directly to its AC adapter and observe if it will boot up or will still shutdown automatically. If it will stay on with just the AC adapter connected and without the battery that confirms it that it's the battery that is faulty already.

Here's a video guide on how to remove the back of your laptop where the battery is located.
https/www.youtube.com/watch?v=ehLioVUkSb0