iPhone wont turn on, PC cant recognize it

You have literally and figuratively “cooked” this board to it’s death.

I would not encourage anyone to reflow IC's on an iPhone logic board, either individually or the complete board. The component density is very high, the pcb is very thin and multi-layered and the components are very tiny. Applying heat without knowing what you are doing is a recipe for disaster. You will cause solder ball explosions or shorts on the underfill-secured IC's.

The proper way to do this is to replace defective components by applying the proper amount of heat with proper tools and experience based on the issue at hand. In your case, you probably just needed to have the Baseband IC reballed and a few jumpers placed.