before shutting down the engine check for battery voltage - it should be at charging voltage - 14.4V..
When you face this failure try to hot wire the starter - remove the start trigger and connect a heavy wire on it jump it to the battery positive, if the starter cranks the the engine you are good in all aspects and the fault lies in either
1 - starter trigger wire
2 - ignition switch.
Honda ignition switches are not the best design.
To test for low voltage - get a 55w headlamp bulb and connect the starter trigger to light it up. It should glow very bright when the key is twisted to start. If its yellowed dim then find the fault.
You can install a relay in the starter circuit to get by as a temporary fix but you will need to find the fault - mostly its the ignition switch.
If the starter failed to engage even when hot wiring it - then get a jumper cable and connect it to the negative of the battery and a chunk on the gearbox casing and reattempt to start, if you get start then you have bad ground