You need to download the firmware from the following location. It has two files, one is a kernel that you need in order to go back.
Download this file:
http://flashman.rpc1.org/Firmware/PIONE ... D/PATCHED/
You also need this flashing utility:
Get it from here:
You put the flashing utility, DVRFlash.exe, the DVDRFlash Shortcut, and the two files R7100007.118 and R7100107.118 in one folder. In Windows Explorer, right click on the DVRFlash shortcut file and click on properties. On the pop up window, click on the "Program" tab and check the "cmn" or the Command line. It should look like this:
DVRFlash.exe -vf G: R7100107.118 R7100007.118
In the above command line, "G" is the drive letter of my Pioneer 107D. If your drive letter is different, then edit the command line to show your 107D drive letter. Click "Okay" when done. Then double click on the DVRFlash shortcut and be very patient until done.