Formatted Micro SD Card as internal storage, after flashing a new build the card is unusable with any device
Use DISKPART utility to create new partitions and reformatting them. I suggest using the below procedure by inserting the card into an adapter and then into the PC.

This is the part which has no Android, but is done on Windows PC. Here we go.


First open a command prompt window with administrative rights. 
An Administrator command prompt will open. Type in diskpart.
Then enter this command "list disk" without the quotes to display all active disks on your machine.
Now choose the disk which is your SDCARD using Select command "Select disk 1".
Type "clean" with no quotes. Hit enter.
Type in "create partition primary", partition will be created.
Type "Active", this will mark the partition as active.
Now, the formatting of partition in format you like, usually SDCARD is FAT32. Type "format fs=fat32 label="NAME THE CARD" quick".
Then type "assign" and then "exit".


Now you have a formatted SD CARD!