S7 Active - "No SD Card Inserted"

[woomonkey]

Hi all,
I just got this phone used, unlocked from AT&T. Worked fine for two days and now it no longer recognizes my SD card.
My Files says No SD Card Inserted.

rebooted the phone several times
tried more than one SD card
verified that each of those SD cards work just fine in multiple laptops
tried a different tray (taken from another S7 Active phone that is also malfunctioning and that I haven't RMA'd yet)
reformatted one of the SD cards into FAT32
the other SD card is exFAT as usual
wiped the phone's cache partition and rebooted
reseated the SD card trays several times
booted into safe mode

the SD card was detected perfectly well 24 hours ago.
I plugged the phone via USB into one of my laptops and selected "Media transfer"... that is when I noticed that the File Explorer (in Ubuntu 16.04) only detected the phone native storage. The File Explorer did not detect the SD card inside the phone when the phone is connected via USB.
Windows 10 PC is the same - only detects internal storage via USB, no SD card.

Any ideas? Thank you!

 

[Rukbat]

That says that the SD port in the phone is bad. It should have at least a 30 day warranty, so ask for a replacement. (You don't want to pay for a factory authorized [meaning keeping the Ip68 rating intact] repair on a phone that's under warranty.)