The problem might be that the phone if faulty and you are out of luck, or that the battery has gone absolutely flat or is faulty and won't charge because of that.

You could try to charge the battery on external charger or compatible nokia dumbphone. Or try to search the forum for other solutions on flat or faulty battery problems. If you have multimeter (voltmeter) you could check if the battery is good. Removing the battery does not require tools and is meant to be done by the user as the sim-card holder is under the battery.