my apple watch won't turn on after charging

See this;

If your Apple Watch won't charge or it won't turn on - Apple Support

This is not helpful advice. It will not force restart. Screen stays black. When on charger, the apple logo appears for a second then disappears....alternating. When off charger, screen stays black. I had misplaced this watch for over a year. Now it won't start. Does battery go bad from non-use?

Yes it's called Negative Discharge and it occurs with all Lithium Ion batteries when they are allowed to be discharged completely over a long period of time.