Slow to start

[bertsmobile1]

Unless you have sealed off the battery cables to prevent water ingression then all of that pressure washing ( which is the most destructive thing you can do to a mower ) has probably caused the battery leads to corrode under the insulation .
Mowers should be blown down not washed down as grass clipping adsorb water and compact when hit with a pressure washer
Unless the mower is stone cold then water will sit on bearings then get sucked in as they cool and the air inside contracts .