HP laptop not turning on without charger

Hey guys! This is my first time doing a thread so please bear with me.

I have an HP laptop that's around 5 years old and I can't seem to turn it ON without plugging in the charger. And once I've turned it ON, it looks fine even when I unplug the charger but the monitor suddenly goes black in a few minutes [laptop is still working but the monitor literally just goes black]. I always need to plug the charger in order to keep the monitor on.

I've already checked it with my IT friend and he says my battery is fine.

I just need to know what part of the laptop is wrong. Is it the power supply? Battery? CMOS?

A big thanks to those who will help.

Your laptop battery is not charging properly obviously. Replace it. The reason it goes black after a min or two when not plugged in is because the battery isn't charging. On an older laptop the battery giving out is very common. You are lucky to have gotten 5 years out of it honestly. I think your IT buddy needs to go back to school, lol.

Your laptop battery is not charging properly obviously. Replace it. The reason it goes black after a min or two when not plugged in is because the battery isn't charging. On an older laptop the battery giving out is very common. You are lucky to have gotten 5 years out of it honestly. I think your IT buddy needs to go back to school, lol.

Hello, I too have a compaq laptop around 5-6 years old and It too is having battrey life of 5-6 minutes the reason for this is that your laptop battery is dead or dying so the only option is to get a new one of if it is a battery other than lithium ion battery then you can try freeze method