Surface Book battery cover flexing

[pcpartpicker]

Hi guys.
A guy is selling to me Surface Book in unknown condition, but a moment before purchase he showed me this on video.
What could cause this?
I suppose battery swelling.
Keyboard cover

 

[Plantje]

I wouldn't buy it

 

[pcpartpicker]

What could cause such issue?

 

[Plantje]

This is something that Li-Ion batteries can do over time. I am not sure as to the chemics that causes this. But the end conclusion is: this is not repairable. The device can be repaired by replacing the battery, but the battery itself is not repairable and should not be used.
A battery that is swollen has a higher risk of ignition. At one time I had an EXOPC/WeTab (Google it if you like to know what it is) with a swollen battery. I have put it outside the house until I found the time to throw it out.

 

[pcpartpicker]

Yeah but you can remove keyboard battery and use the one on tablet side...
I mean what you want, guy is selling it for just 180 euros....
I am sure you can use it normally when keyboard batt removed.

 

[Plantje]

If you can remove it, remove it. Don't use it whilst bulged