Have you tried downloading the new bootloader from the previous post?
I had great success loading the new bootloader to the BLE Nano. All you do it drag and drop this file "SoftdeviceS130-1.0-Bootloader-20160824.hex" from the folder to the mbed MSD. It disables the DFU mode.
How are you loading firmware onto the BLE Nano? Arduino IDE, MBed?
If you are using the Arduino IDE you will need to select the alternative BLE Nano (v1.5, 32k) in the board list. It was located at the bottom of the list of Boards in my case.
All the best.