Boot animation upside down after new ROM
If you can bear with having to turn screen off/on once the device had booted up, and just want the bootanimation to look normal, that's quite easy - just edit the bootanimation itself to make it upside-down.


Grab and extract /system/media/bootanimation.zip.
Rotate every extracted image by 180 degrees.
Recompress the extracted files, keep the structure (compare with the original if necessary), and choose "storage" when asked about compression level (any actual compression will prevent Android from reading the file).
Place the modified file back to where it was and set proper permissions.