NEED HELP-INFINITE UPDATE LOOP

Hi, just to be clear, i have a mac (OS X 10.12.6) So yesterday i opened my League client and i saw this text: „We have restored the installation to an older version...Now we'll try to patch it up to the latest version.” Ok so i downloaded the 1.9 mb update and the client re-opened. But when it opened i received the exact same message again and the update started again. There is nothing i can do about it, it's in an infinite loop. I've tried restarting the computer, setting the time back and i dont kniw what else could work. My internet is fine, so if you have any advice, please let me know. Thanks!