I pressure washed under the bonnet on another car once. It washed most of the grease out of the alternator bearings and ceased it solid. It just made a clicking sound as the starter could not turn the alternator! Had to replace the alternator as a result because re-oiling didn't really help.

I would be very careful when washing under the bonnet on any car now.

Hopefully your problem will go away with a bit of use, but if it persists, it might be worth looking at the starter solenoid, or even the alternator like me if it is ceasing! Maybe try a bit of WD40 on those sort of parts!

Good luck.