By default Radarr installs with the radarr user, but other plugins like transmission / sonarr / etc. require the media user. If you change the user to media then radarr does not start / boot and does not show any errors. Follow the guide to fix it.
How to fix a Raspberry Pi that wont boot and is showing the "cannot open access to console" error message.
Installed windows on another drive then removed it? Have two boot drives and one has stopped working? Getting blue screen error at startup even though you have a healthy boot drive 0xc000000e. This should help resolve it.
Getting a NTDLR error after removing a hard drive. You are probably missing a boot record. This is an easy fix.