I have a Phantom 4 Pro+ Obsidian, and am now able to upgrade and downgrade to any version I like, even from the latest totally locked V01.06.0910 with its Anti Roll Back value of 4....   If anyone has this rubbish version, or the equally bad previous nightmare version V01.05.0600 and you can't downgrade.... message me.
I have managed to downgrade mine to what is reported to be the most stable version available, V01.03.0509.
Now when I fly, the screen doesn't freeze, and go green, and constantly chop and change between previous frames making it impossible to fly...

Have found a weird Hand Controller version that gets rid of most of the issues with versions V01.04.01.00 and GL300E_v1430, but I'm not sure where it came from. It isn't a DJI version. The official versions report NO SIGNAL on 5.8GHz and to move the antennas, even though the drone is 1 metre away and it'll still fly over 2000 metres away just fine, all the time reporting no signal even when I return to home and land. This weird version reports no issues at all with the 5.8GHz signal, so I'll keep using it until I can find the original version the HC came with.... no luck so far (don't recall what version it was).

Hey help me please

You will need to download a program called DUMLRacer.jar and run it to remove the DJI lock out code. You will need to watch youtube video's on how to run it as it is a bit tricky, but I can't tell you more than that.
Then you will need to get a program called DUMLDore.exe to install the old version. It is easy to use once you have it on your PC as an exe file (doesn't need to be installed, just copy the exe to your desktop).
And you can download the old version for the Phantom 4 Pro by running a program called DankDroneDownloader.exe
In summary: Dowenload the 3 programs 1. DumlRacer.jar 2. DumlDore.exe 3. DankDroneDownloader.exe. Then do the following steps in order:-
Step 1 - run DUMLracer.jar
Step 2 - download the old version of software you want with DankDroneDownloader.exe
Step 3 - Install the downloaded old version with Dumldore.exe
Watch this video as well. It says MAVIC, but it works for PHANTOM too.