eventhough this problem is a past few years ago. i just want to share how i fixed my microSD. i encountered all the problems that mentioned here. i tried formatting my micro to a different OSes, bunch of softwares which gve me the same error. then i said to myself i got a rooted htc phone which has an 4EXT recovery on it. i got 3 samsung device that has twrp and i never got my micro to get fix even cwm. so after almost a day banging my head trying to fix it. i inserted my micro to my old htc phone, and went to recovery, at first boot up it gve me an error that my micro sd won’t get mounted. so i just let it boot up and when i’m inside the 4ext recovery i pick format sdcard. and it won’t gave me an error. after i’m done formatting my micro i put the microsd to an adapter and check it on my linux and the red exclamation point was gone. so try it for yourself guys! 4ext.net goodluck!
