XPS 15 9550 new replacement battery not working

Hi!

I have an XPS 9550 laptop. My battery started swelling a few months ago and as you probably know Dell is not replacing swollen batteries anymore when out of warranty for this model. I had a hard time getting a replacement battery because Dell's support in my country (Argentina) is virtually non-existent and the authorized retailers Dell suggested to me sold the batteries at twice the real cost ($220 for the 56 Wh model). So I ended up buying the battery online in Chile when I was there for other reasons a few weeks ago. I got the 4GVGH model (84 Wh) and installed it a few days ago.

After leaving the laptop plugged in with the battery charging for a few hours, I tried unplugging it and it stayed on for a few minutes, then it shut itself down suddenly. Since then most of the times the laptop won't turn on unless it's plugged in. Some times it does and stays on for 30 minutes at most, then shuts down. The strange thing is that when the computer is plugged in, battery health reports show no problems and say it's fully charged and healthy.

Does anyone have any idea of what could be going on? Does it sound like a problem with the battery or with my laptop? With my old battery I never had this problem. Even when it was swollen and charges were lasting shorter than usual, it stayed on properly when plugged off until I removed it for safety reasons.

Thanks a lot in advance!