No idea what a gap block is but the phone has FRP Lock enabled.
+
So, when you get the message 'Custom binary blocked by FRP lock' it means you have flashed a unauthorized binary file to the phone and the phone is preventing itself to boot since it has detected the modified file(s).
-
Only way to remove is via original owner of phone or having proof of purchase and taking it to Samsung.
+
Now to fix this to at least boot up properly you need to reflash the Samsung Firmware for your phone.
-
FRP Lock enabled blocks custom binary flashing and prompts Samsung or Google account login that was link to the phone during activation setup wizard after factory reset.
+
Match it to the model number shown on the back cover of the phone (SM-G9xx for example) or model number shown in download mode which you can access if you keep holding power + volume down + home until you get to light blue screen.
Note that in most cases you will need to downgrade the firmware on the phone back to Android 6.x Marshmallow if you are already on Android 7.x Nougat for the FRP bypass method to work.
No idea what a gap block is but the phone has FRP Lock enabled.
Only way to remove is via original owner of phone or having proof of purchase and taking it to Samsung.
FRP Lock enabled blocks custom binary flashing and prompts Samsung or Google account login that was link to the phone during activation setup wizard after factory reset.
FRP stands for Factory Reset Protection.