Take a really closeup look at the charging port in the laptop.
Is there a centre post? Probably is one.
If so, then remove the laptop battery and proceed.
Look at the post. Does it have a split in it? Meaning that the post is not solid metal but 2 halves. If so then very gently slightly separate the two halves with a thin implement. Test connection. Repeat if necessary.
MOST charging sockets do NOT have center pins its a relatively new thing...