Safe mode works, normal mode loops

[DeDrongo]

I'm at a loss, my Macbook Pro (2015 model) running El Capitan crashed, then had a weird pixelated screen and basically stopped running properly. Decided to upgrade to High Sierra, didn't fix a thing (added some other problems), rolled back Timemachine a couple of weeks to restore El Capitan. This fixed (most of) the pixelation, but now I can only boot up in safe mode, in normal mode it shows the login screen, I log in, it starts then pretty much straight away logs me out again and so on. Safe mode works, I have unchecked all login items, cleaned with Onyx, used Bitdefender to scan etc etc., no dice.
Any suggestions would be most welcome.

 

[Fishrrman]

When the computer boots fine in safe mode...
BUT
WON'T boot in "regular" mode...

... then something, somewhere in software that you installed is mucking things up.
It could more than just a "login item".

This can be vexing to fix.

There's a utility called EtreCheck that might help in the search for what's wrong.
You could download it, run it, and post the results here.
Perhaps someone will see what's gumming up the works.

Sometimes the only way to "extract yourself" from a mudhole like this is to create a NEW account for yourself, and slowly, gradually "move things over" from the old (malfunctioning) account into the new. Do it A LITTLE AT A TIME and observe how the computer runs between each move.

Try EtreCheck first.