Battery broken librem 15

I bought Librem 15 laptop in 2017, 1 year later battery got broken, i mean, my laptop need be plugged in the charge all the time otherwise it will turn off, so i think its the battery?
it came to that point I not being lazy anymore and want a working battery,

What I need tell to the computer maker in store what he need to fix? What kind of battery will i need to replace?

I suggest you ask Purism support directly on