The iPhone 7 generation is notorious for cellular issues. Most "invalid IMEI" or "Searching..." errors on this model are caused by hardware failure, not corrupted software.
Before attempting a repair, it is important to understand why the IMEI (which can be found in Settings > General > About ) might show as "Unknown" or become null:
Advanced tools like Z3X , Medusa , or Octoplus Box communicate directly with the iPhone 7’s Baseband CPU via JTAG (Joint Test Action Group) protocols.
, particularly models with Qualcomm basebands, involves the .