How old is your battery? It is not enough to charge it if it is old. I've read about modern accumulators or supercapacitors https://supercaptech.com/battery-vs-supercapacitor/ and they say that the latter can be much more reliable sources of energy.
If it's not a battery, then check the starter, maybe the whole problem is hidden in it.
Vw Caddy Tdi 1.9 Van Won't Start Is It The Fuel Pump? I Recharged Battery (after Trying To Start Vw Caddy To Many Times!) But Air Got Into The Injectors. I Got Air Out Of Injectors. Battery Ok, But Now Engine Will Not Start When I Turn Over Ignition?
This may sound crazy but did you check the gas cap. My sister spent almost 800 dollars trying to fix a fuel problem only to find out that the fuel cap was broken(did not seal properly).apparently the fuel system is pressurized and needs the cap to make the tank a sealed unit for the pump to work properly.I know it sounds crazy but after they replaced a 25 dollar gas cap the car ran perfect.