Ok.  I removed the left side engine cover to polished it. Reinstalled the engine cover and I have this problem.

After I tighten the bolts for the engine cover and try to start the engine, you can hear a click from the starter selenoid, but it won't turn the engine. I thought it was a low, bad, or dead battery so i bought a new battery and had the same results. I removed the engine cover again and reinstalled, but this time I didn't tighted the bolts. Then starter works, engages and turns the engine. As soon as I tighted the engine cover again, I have the same problem, you can hear the started clicking but it will not turn the engine. I again loosened the bolts of the engine cover and the engine turns.

What am i doing wrong? Seems like when I tightened the bolts, something (starter gear or starter clutch) get jammed some how?

Any suggestions or solutions?

Yep, you got the washers in wrong.

There's an idler gear, no washers on this one.

And a spur gear, a big one and a little one together.  Washer goes on either side.

that should fix you up.