AVM Fritzbox 3290 USB Stick not recognized - red info LED flashing

I had this problem with different USB Sticks - no matter if I formatted them with ext2, NTFS, FAT or FAT32. It was always the same problem. An error message like this one:

• Der USB-Speicher 1002 enthält kein unterstütztes Dateisystem oder hat eine ungültige Partitionstabelle.

Today now I finally stumbled upon the solution. You will need two tools to solve this problem:

• h2format
• hxd hex editor

Both downloads can be found at heise.de for example.

When you got HXD installed and h2format.exe in a path that you will easily find again do the following:

• Plug the usb stick into your Windows PC and make sure it is formatted as FAT32.
• Now start HXD as administrator and go to the Extras - Optionen Menu:

• When you did this open your USB Drive with the small Icon in the menu bar:

• Now all you have to do is overwrite the last two hex blocks in Sector 0 with "00" and hit save:

• After that you start a new dos box (Wndows key - R - cmd.exe) and change to the directory where you put the h2format.exe and enter "h2format.exe X:" where X: is the drive letter of your usb drive.
• When finished your USB drive should run just fine with your fritz box.