My Mazda Protege won’t start...Help!

[Pmazda5]

Hi, I charged battery and polarity reversed now car no start anymore. Any idea where to start to diagnose this problem. I obtained a good battery but no power to starter. Only lights that come on are dash speedometer. Thanks!

 

[Pmazda5]

Checked fuses and main fuse is blown so will get new one and go from there.

 

[Pmazda5]

Changed fuse and everything is fine, thanks!

The main fuse is under hood, right side of engine, it can’t be taken out unless the 2 - 10mm bolts are unscrewed.