@WhosMac,
@CaseySJ
I finished the install and reproduced the initial 10.15.1 result now with 10.15.2. So a fresh Catalina install with an
already installed 5700XT is possible with both versions and reproducable. No need to leave the GPU out and install with iGPU.
Steps (in short):
1. Create an USB Install-Disk with Catalina
2. Use Clover 5100 with the customized settings accordingly to the mini-Guide
3. Copy the Files from
Catalina Fresh Install Folder supplied with the mini Guide to the EFI Folder of the Install Disk
4. Copy Config-AMD-GPU.plist to the EFI Folder of the install disk and rename it to config.plist (set -v before if you want to follow the debugging)
5. In BIOS set the Installer Disk at the top of the boot sequence (DEL -> F2 -> Easy Mode -> Boot Sequence) This was the game changer for me. I did not do that before, since I always got the clover screen anyways and could choose the installer disk. Nevertheless not doing so so reproducably resulted in hanging/freezing/black screen and not launching the OS installer.
6. Boot from the Installer disk and follow the debugging. When the "services exited with abnormal code: 1" is stated and it seems to hang. Wait for a minute, the screen will go black and after 1-2 min the installer will launch.