How to investigate the car that is not starting?

What is your question?

The car is cranking and I charged the battery but not starting. The radio also not starting. I am not able to push the gas pedal as well, the car fails by that time. before charging the battery when I start, I hear" tak tak tak tak "noise from the engine. The car has been sitting for a few months since the pandemic but usually, I was able to run it by charging the battery. I think since the car is cranking the battery is charged. I connect the wire to charge the battery in a wring format and heated the wires. so that might have done something.

What makes this problem better or worse?

charging the battery

How long has your 1998 Mercedes-Benz ML320 had this problem?

a week