I disabled the Addon Manager and it started perfectly, without me having to tamper with the OldScenery.cfg and SceneryStatus.bin
But since this doesn't happen to anybody else, it's clear there must be something unusual in your installation. The Addon Manager DOES NOT touch or even tries to read these two files.
The Oldscenery.cfg file is a backup used by the sim in case your main scenery.cfg gets corrupted but, again, even if the Addon Manager is reading from it, it doesn't WRITE to it so, it cannot corrupt it.
But some other external utility you might using to handle the scenery.cfg, which hasn't been updated to properly support P3D V4, might be the cause of the corruption, which forces the sim to use the Oldscenery.cfg. Most likely, an utility that doesn't recognize the scenery.cfg file encoding, which has changed from Ansi to UTF-16.
The scenerystatus.bin is also NOT read or used in any way by the Addon Manager, but it's used by the sim to store the last modification date of the sim scenery cache. Again, we DO NOT interact with this file, at all, but (again) a 3rd party scenery configuration editor will cause such file to be modified.