New battery, new solenoid, won’t start and battery is dead

Craftsman Pro Model 247.270551 lawn tractor. Replaced the battery after constant boosts. Mower initially started and ran with new battery until I stopped and turned the mower off. Attempt at start is met with silence and the immediate drain of the battery. Gage showed normal live battery until I turned the key and then it all went dead. Recharged the new battery, replaced the solenoid, tried to start and met with same results. A quick visual flash of battery life as I turn the key and then dead. No motor turn. No clicks. Just….dead.

Disclosure: I’m not a handy man, a shade tree mechanic, or even mechanically inclined. Just muddling through what I can do. The almighty Google leaves me not knowing what to do next or what the most likely cause may be so I can just fix it and move on.