[Q] Is my S5 real or fake? topic

I know I'm probably just being paranoid from watching too many videos of near-perfect S5 clones, but here goes... I just got a Charcoal Black 16GB SGS5 (SM-G900F). From what I have seen so far, it has all the features a real S5 should have, such as a working fingerprint scanner, air gestures, Air View, NFC, or a slow-motion camera. The screen is vibrant and responsive, and the flash/pulse sensor looks like the real deal rather than a sticker. The device automatically downloaded an update after I connected it to WiFi, and I was able to import the contacts from my old S2 using Kies. I ran the Phone Info app, which informed me that it is a genuine Vietnamese-made phone with a Qualcomm processor. However, there are a couple things that bug me. First off, the sticker underneath the battery does not state the device's country of origin, it just says "Made by Samsung" and "Samsung, Yateley, GU46 6CG, UK" (which appears to be Samsung's European QA lab). Also, while the IMEI on the sticker matches the one on the box and the one that shows up when I dial *#06#, it belongs to a 2004 LG flip phone according to imei.info, and a couple other IMEI check sites couldn't recognize it at all (only one identified it as an S5). Moreover, although the phone responds to most Samsung codes, there are some that don't work - for example *#0011*# (which someone on here said meant the phone is fake).

Thanks you in advance for your replies!