Chris pelf

My son has a 2000 Lexus rx300. His radio stopped working. He removed the screen and the preset buttons for the radio and cut the ribbon going to the radio and climate controls. Added a aftermarket radio. Now his AC and heat does not work. My question is this. If he buys a whole new assembly. Screen, radio ,climate controls, bezel etc. used off EBay. Can you just plug and play or will there be any programming that has to be done for it to work again.