Unless I’m reading it wrong or interpreting T-Mobile’s document wrong, I don’t think the trade-in policy disqualifies back glass crack.
I’m talking about this T-Mobile support document
Checking your device condition
There are four main things to check on your device. Click each link to learn more.
Device turns on (Not required for buyer's remorse or warranty exchange)
Screen & LCD damage
Screen damage (LCD or display damage) voids all warranties and can't be accepted.
- When inspecting a screen, remove any screen protectors and cases first. Tilt the device under good lighting conditions, and inspect at multiple angles. Screen damage includes hairline cracks that are difficult to see.
- Screen damage includes:
- Cracked screen
- Cracks or chips in glass that is connected to the screen (including edges)
- Crushed or shattered screen
- Not readable, pixelated, or distorted display
- Screen replacement or repair through an unauthorized third-party
- Scratches and scuffs can occur from normal use and can be accepted.
- Examples (click images to enlarge)
To me, this is pretty clear that back glass doesn’t constitute Screen & LCD damage. I’m being told different things in-store and over the phone so I’m trying the community to see what the actual policy is.