Just an Idea
You can install the SafeStrap apk file using the ADB (Android Debug Bridge) "install" command, as long as adb recognizes your phone. You can download everything you need from here
. Although if you can't boot up your phone I don't see what you could do with the apk installed because you can't open the app to press the install button.
Quick tutorial on ADB:
1) Download the file above.
2) Unzip and navigate to the sdk folder > platform-tools.
3) Hold shift and right click inside the platform-tools folder. (Make sure you click on an empty space inside the folder, not on a file.)
4) Select "Open command window here".
5) Run the install command which you can find information on here