"Old" AR3 with dead 3.5 Teensy. Is the 4.1 plug and play?

Hello,

I have an AR3 wih CUI encoders. It's been sitting for a couple of years. I tried to fire it up and it looks like the teensy 3.5 is dead. I ordered a 4.1 as that is what seems to be in the newer units.

What has to change to integrate the 4.1? Wiring? code? the HMI application? I would appreciate any links that you think are useful. I assembled the unit, and used to know a lot about it, but years later, I'm totally new. Any advice would be appreciated.

Thank you in advance.