"HELP! Logic board physical damage"に関する回答Looks like a possible puncture to the logic board, and exposed the micro-components inside. Replacement logic boards are available thru iFixit, but if you decide to go to an Apple store, it’s not repairable and they’ll have to replace it out of warranty for $400.
"Which component is responsible for connecting to the mobile network?"に関する回答To rule out software, a full restore and set up as new to test connection will help to tell you definitively if it’s sn issue with the hardware. If it’s still searching after that. To rule out SIM card - test the sim in another device (if you have access to one). Or try a new SIM card (you can get one at an Apple Retail Store or carrier store) and try to activate it. If you want to open the device and test connections there, you can re-seat the coax cable that connects to the logic board. Sadly you can’t replace an antenna as it is built into the plastic enclosure of the device.