Dead battery sony vaio laptop PCG-71XM

Hello all was wondering if anyone could help with a latop a friend asked me to repair its a Sony VAIO laptop PCG-71XM which will not power on (no powerlights are displayed).
I have tested the psu with voltmeter and its reading ok and i have also tested the rear of the terminal inside the laptop and this is reading the correct voltage comming into the laptop.
One thing to note is the charger is a replacement one and on the back it states its a Qubz AC charger but it doesent state the output as AC it just says output 19.5v=4.5a and the laptop says it requires a 19.5v DC charge, now my friend claims they have been using this charger for several months without a problem.
My questions are this.

If it is the AC charger should it have worked at all.
If so would it have damaged the battery/laptop after prolonged use.
Should this laptop work without a battery or with a totally dead battery.

Thanks in advance for any advice offered.

 

= symbol means DC. If it was AC coming out of the PSU, you probably would not be able to measure it with your voltmeter set to DC.

Laptops usually do work without a battery just with the charger plugged in.

If I were you I first would check if the power jack in the laptop is loose or something (broken contact). Second try another PSU (given that you can measure 19V does not mean that it provides enough amps under load at all) or try this psu with another laptop or an appropriate load (e.g. 24V halogen lamp). 3rdly, check if the power button of the laptop is switching properly.

If all this does not show any issues, you might have a hardware failure and you need to open your laptop and dig way deeper which is a serious amount of work.

 

Thankyou for the quick reply just goes to show you what an amateur i am, didnt know about symbols on the charger and forgot the basic's of using a multimeter think i better stick to just fixing desktops after this.
Looked at a few charger's around the house and they all have AC on them but again the symbol is for DC well you learn something new every day.

As for the laptop i have had it in bits and tested the power coming out from behind the inlet and all is good, no power on lights at all so that rules out the switch, so guess it will have to be the charger next but typical sony the power inlet is quite an obscure type and none of the universal charger bits i have fit so guuna let my friend decide if they want to go spend some money.

Thanks again for the quick reply.