Camera will not power on at all. Battery has been replaced already.

Mostly camera has a issue that after longtime not use and battery is in then the connection between battery connector and battery has rusty.So i suggest you first clean battery connector where battery connect.

Make sure you charged the battery for the correct time and also make sure the battery is in good condition (some "new" batteries may be faulty). Measure the voltage across its terminals and see if the voltage is the rated for the specific device. Also check the charger; the voltage across it terminals should be somewhat higher than the battery rated voltage. If the battery seems to be the problem return it to the supplier and demand replacement.