I’m a recent convert to G7 having used the two samples my Endo gave me as a trial. Based on those, I asked my Endo to prescribe via the same Tricare pharmacy I get my Dash pods from and I picked up my first 90 day supply last Monday. I’ve entered one correction on the second G7 within 12 hours of putting it on; I’ve done only 4-5 finger sticks with all being 2-15 pts with the G7. I consider that well within a 10% variance of the finger stick, which itself can be off. I believe the issue is meter placement, meter/test accuracy, personal chemical make-up, and the fact all systems…whether lab, CGM, or personal BG meter…have a level of error built in. It’s not that I don’t believe some of the wild disparities in numbers some report (I experienced those a few times with G6) and I’m presume I will with the G7; but as long as my numbers match my moods and the system is accurate/precise most of the time, I can live with that until the science improves.
Number 3 began acting up 9th night. Over and over loss of signal.
I got an email from Dexcom on the one that failed at 5 days. They wanted the serial number or it would use one of my good Will replacements. Fortunately I keep the box and applicator.
Good for you err not that the G7’s failure but that you kept all the goodies in order to get the appropriate replacement. A good lesson for us all.
I always kept the label from the G6. Now I’m tearing off the flap from the box that has the pertinent info. I date the start time/date.
Doctor @CarlosLuis do you make house calls 
Part of my telephony career was as a cable splicer. I can tape anything. 
If you ever find yourself without the Dex numbers you need, just give them the number off the next one you are going to use.
I know it’s not the one that failed, but all they need is a valid number. That keeps you from getting ripped off by not getting a replacement!
Yippee-ki-yah Cowboy You Da Man
with a roll of duct tape, vise grips & a knife you can fix just about anything…
Unless you are 200 mile from any town & your Jeep broke a tie-rod. Duct tape just won’t hold when you are rock crawling so you need two 12v batteries connect in tandem, a pair of jumper cables & a stick of welding rod…
at least that worked for those two guys on Doomsday Preppers 
Oh my that was a hard swerve off topic. sorry 
I think I broke a tie-rod
Easy way is to take a pic of the labels and with the date you can recall all you need.