MacBook Pro 13 2013 - Grey Screen Installation

Hey dear community.

Yesterday I wanted to erase everything on the disc and prepare so I can pass it on.

I had Sequoia on it before with OLCP but read that properly erasing it would require reinstallagion including wiping the SSD.

Saying that, updated the OCLP app and als wiped a flash drive with 64 GByte.

It took me multiple attempts to flash the drive with the needed installer and then all needed steps as per webpage and also multiple YouTube videos.

1. I have the drive plugged into the notebook.

2. I booted the notebook with holding alt key

3. deleted the EFI of the flash drive

4. selected the install Mac OS sequoia from next step

5. wiped the internal disk

6. went back and chose install

7. selected language

8. continued and sometimes it goes back to the selection ig I want to install macOS or wipe disk etc

9 selecting install macOS leads me to a grey screen with only the mouse curser available

Nothing else happens. I am just stuck there.

I can shutdown and restart the procedure and nothing happens.

Anyone can spot mistakes I have made?