I can't speak to this laptop in particular, and I'm too lazy to look it up, but I know that getting rid of BIOS lock passwords are more difficult on Dell laptops than just removing the battery. Most of them store the password in NVRAM in the TPM module (ie it doesn't need a battery to maintain the password). In most cases you need special software from Dell to clear the password out. For obvious reasons, Dell does not freely distribute this software and will be reluctant to give you it even with reasonable proof that the laptop is owned by you.
To the OP, your best bet is to contact the original owner and get the password from him/her. In the past I have scoured the internet and couldn't find Dell's password removal utility. I had a couple laptops at my work that I had forgotten the BIOS password (yes I was the one who set it) and I just couldn't get into them. Luckily I finally remembered what I used for a password and summarily disabled the BIOS lock. What I discovered is there are quite a few people claiming to have the software, but they expect you to pay for it up front before they will e-mail it to you. Smacks of scam to me. Worse yet, you don't know that what their sending you isn't a trojan/virus/keylogger or whatever.