Bought tf2 today, won't launch: File Corruption Detected ever after repair

I bought and downloaded the game through the origin launcher (in the same session). 46gb download, get a splash screen for respawn and EA then a dialog box:

Title: Engine Error

Text: File corruption detected. Please repair or re-install the game.

I repaired the game. It says it's fine. I launch it (several times, including after reboot). Same error.

I read something about language, but the language of the game and my system is the same. I don't even recall an option to select a language other than english or chinese on install.

I have numerous other games installed and working fine (including Apex Legends through steam, and it's been installed and working on this machine before via Origin). Drivers up to date etc.

Terrible experience obviously. How do I remedy this or get a refund?

Thanks.