Look at the technical support page:
https://openthings.freshdesk.com/support/solutions/articles/5000859137-troubleshooting-and-technical-help
and scroll down to the question about “My controller’s LCD went bad. How can I get it replaced?”.
Here’s a link to the right type on Amazon:
https://www.amazon.com/HiLetgo-Serial-128X64-Display-Color/dp/B06XRBTBTB/ref=sr_1_5?dchild=1&keywords=I2C+OLED+0.96&qid=1627195847&sr=8-5
You can find the same thing on ebay or AliExpress for much less but then it’s shipped from China and it takes about a month to arrive.
Also, update your controller’s firmware to the latest version – they added a feature that turns off the OLED screen unless a button is pushed.