Good news !
Incredibly enough (with the help of a friend pressing various buttons on the front panel + reset) I managed to get into the flash menu and flahsed the 2.0 version .bin
Chuck: You can't really make a complete backup of the AVIC as it is. You need to copy "My Flash Disk" and get the .img and .chk from the last firmware you flashed to it. In my case its AVIC-F500BT_Firmware_Update_2.006000.zip
There might be a way to get it off from the AVIC, I recall there used to be a WinCE/Mobile app that dumped the rom to an SD-CARD, will try to see if i can find it for you. But the easiest is getting the firmware from Pioneer (or here if you used any of the "unofficial" ones.
BTW, altho i did not use either of the posts you said the info inside was great reading so thanks for that
Good for you my friend .
I am just wondering why do you want to go back to FW 2.0 . Your problem has nothing to do with the FW version.