Samsung S5 Switches Off Instantly After Inserting SIM: Please Help

[Android Central Question]

I'm brand new to smart phones, and recently upgraded an old Orange Rio to a Samsung S5. I purchased it second hand from eBay, and I think it's possibly locked to o2. Today I got my new SIM from Virgin Media, my current provider, and after inserting it into the S5, when ever I start the phone, I get a message saying

"Unable to use fingerprints. Device Restarted. Enter backup password, then fingerprints can be used next time device is unlocked."

However the screen shuts down within a second or two, but always before I can enter the password. I have tried removing the SIM to see if that was the issue but it's still doing it.

What is happening please?!

 

[B. Diddy]

Welcome to Android Central! Did you actually set the phone up with your own Google account first, or was this the first time you tried starting the phone? If it was the first time starting the phone, then it sounds like the previous owner might not have properly removed their Google account before doing a factory reset.