Chosen Solution
I received an iPhone 7 Plus to repair and resell. It isn’t set up yet, but it keeps searching for a signal, while the sim card isn’t inserted. Inserting a sim card doesn’t make a difference though, it keeps searching for a signal. When I try to set the phone up, it tells me “Unable to Activate” (see the picture below). Does anyone know what the problem might be and what I should check? What should I check with my multimeter? Is this the baseband chip that’s causing problems? I am new to logic board repair / micro soldering, but I do want to do it myself and I got the equipment.
Your phone has more than likely had a failed audio IC repair. The audio IC has had too much heat applied to it causing the Baseband CPU’s solder balls to expand resulting in the problem you are having. This has nothing to do with the Antenna. If you type *#06# into your keypad does the IMEI display? If it doesn’t it will confirm it. There is no simple fix for this problem unless you are an experienced microsolderer.
Check the antenna bars. They might be obstructed. If that doesn’t work, try ejecting, cleaning, and re-inserting the SIM card. I personally don’t have 7 plus, so this is some minor textbook stuff that not everyone knows.
