Scan tool would be handy to get whatever DTCs are being flagged.
Otherwise, if it is actually trying to kick the starter briefly and then craps out, check battery voltage with a multimeter before and during that cranking. If the battery is in good shape, you should expect around 12.2-12.5V before cranking and no less than about 11V or so during cranking.
If the voltage remains at the non-cranking measurement you made, then you likely don't have power going to the starter. Next, check the relay coil input to see if it is receiving 12V across its coil. If it is, check if the relay itself is indeed clicking and check the power coming out of that relay going to the starter. If you see power leaving the relay, then it must be getting to the starter but perhaps the starter has gone bad. If you don't see power leaving the relay, then it's a bad relay.
We had another dude here have a problem with their starter relay, of which I believe there were two of them to contend with. From memory, they're like $45 a piece from the dealership or something but let's not get ahead of ourselves and just start with those basics.