If disaster ever strikes, and you find you cannot start up your T2 equipped Mac, it helps if you have made a few preparations. The T2 chip that is built into modern Macs provides a number of important features, including security features. By default, this security is very tight, similar to using iOS on an iPhone. This prevents starting up from any external drive or anything other than the current signed OS available from Apple.
Techtool Pro users need more freedom than this security provides, and fortunately, a quick trip to macOS Recovery provides this freedom. After starting up in macOS Recovery, launch the Startup Security Utility, and use it to reduce your Mac’s security. More details are available here.
Once your security settings are in place, you can start up your Mac from an eDrive or Protogo device without interference from the T2 chip’s security settings. From there, you will be able to use Techtool Pro to troubleshoot your Mac should a disk problem prevent starting up your Mac.
Pro Tip: Be sure to set your security settings prior to creating an eDrive or Protogo device to ensure that they will start up your Mac properly.