First time upgrading P3 Professional so I chose FW_V01.03.0020 before the latest version. Here are my steps:

1. Format the original card in P3
2. Download version FW_V01.03.0020. Extract .bin file and load on to the sd card (on a mac).
3. Insert into P3. RC is off. Power up P3.
4. Lights flash green-red and short beeps. After 10 mins the beeps become one continous sound and only red light on the gimbal.

I repeated six times. Sometimes I reformatted card again. Tried other cards.

In the App it states the firmware version is unknown.

Txt files keeps stating
========== 2014.01.01 00:00:13 remo-con disconnect======
Packet: P3X_FW_V01.03.0020.bin
Upgrading ...
Result: Failed.
Reboot the aircraft and try to upgrade the firmware again.

I decided to go direct to version 1.4 and manually upgrade the RC to 1.3.2
It almost worked. After 8 attempts for version 1.3.2 where the P3 just kept beeping 4 times then failing on version1.4 the P3 made different sounds and the start-up sound... the gimbel stopped and started... lots of different stuff which is the normal process. Then the red light and failed.

Now I have the RC at 1.3.2 and the aircraft at... nothing.

Bit of a mess and I stopped for today after five hours. Thsi failure rate at upgrading is just far too high and I cannot believe it is user error.