Suspect I was scammed on battery replacement, need some input

I had my Nexus' phone battery replaced today, or thought I did. Before replacement, the phone would shut off when it got to around 50% or so. The battery would drain a lot more quickly than when I first got it. It had great battery life at that time, but recently the drain has been so quick I needed only to watch the battery life indicator or AccuBattery for a minute or two to watch the number drop.

In any case, I took my phone to a repair place today and they claim to have replaced the battery, but I see zero difference in battery life. I am not sure if the screen protector would have needed to have been removed while replacing the battery, but if so, my original screen protector is still in place.

Can someone give me some input as to whether it is likely that I was scammed or if it is instead possible that I have some other hardware or software issue that is causing any battery in my phone to drain super-quick?