Reset flash drive

Use something like Gparted and delete all partitions on your flash drive and just make a new single primary partition.

If you have GNOME just go into Gnomedisks select the drive and choose the format option. Or as somebody mentiomed Gparted is great but there are some things to learn for table, partitions, flags etc

Block devices are simply devices that hold data. That's all. For a block device to be "formatted," you typically want a partition table, a partition, and a filesystem in that partition.

For flash storage, the most common off-the-shelf solution is a DOS partition type with a single partition that occupies the entire storage, and a FAT32 filesystem.

On larger or more modern devices, you'll typically see a GPT partition table with a single partition with exFAT. This setup allows you to store files larger than 4 GB.

You can simply use fdisk to create or modify a partition table and create a partition. You'll want to use a mkfs tool to create the filesystem.

...

$sudo sgdisk --zap-all /dev/SD{x}

$sudo wipefs -a /dev/SD{x}

The first wipes any existing partitions or data that exist.

The second wipes any data in the table headers if anything is left?

Those have worked for most times I needed it

sudo gparted /dev/sdX

You have blanked the partition table, gparted can create a new one with a friendly GUI

Use a partition manager like parted or fdisk to delete all the partitions from the drives and create one new one that encompasses the whole disk.

If you are doing all this from a GUI you can use Gparted to make it easier for you.

Does the flash drive show when you run lsblk with the correct amount of space? dd will overwrite the partition table and works directly with the underlying physical blocks of the device. If the flash drive isn't broken, you should be able to rebuild the partition table with parted (tutorial from linuxconfig.org on the matter)