Do not keep attempting the same restore over and over. Each failed flash stresses the NAND chip. Follow this guide line by line. If you reach Method 7 with no success, accept that the issue is hardware and seek professional micro-soldering services.
The restoration process fails because it cannot verify "subpar" battery health or encounters a faulty charging cable/port. Software Interference: error unable to restore idevice--75- 3utools
If the main system restore fails but you suspect a baseband issue, you can use 3uTools' "Pro Flash" features. Do not keep attempting the same restore over and over