laptop battery question

I am hoping this problem has a factual answer, why I am posting it here and not IMHO.

We have a laptop, an HP Pavilion (purchased and in use since 2005) and have recently replaced the battery.

Laptop will start up just fine when using only the battery (when power cord is disconnected); Or laptop will start up using only the power cord (with the battery removed).
However it will not start up while battery is in place AND the power cord attached/plugged in.

We cannot make sense of this. Is anyone familiar with this issue? I’d like to add that once the laptop is started up - if using battery, power cord can then be attached with no problem to the operation of the laptop. Or after starting up with only power cord, then the battery can be put in place with no problem, laptop keeps working fine.

But the pc will not start up while battery is attached and in place AND the power cord attached.

Did you get a OEM battery? If not lots of wonky things could happen like what you describe though most do work fine.

this. in some cases, the OEM battery has a chip inside it identifying itself as an OEM battery. If a third-party battery is plugged it, it won’t identify itself properly and the charging circuitry in the laptop will refuse to charge it. I ran into this with a Sony W-series netbook; found a “standard capacity” battery for it on Amazon which turned out to be some shit Chinese knockoff. Out of the box it didn’t charge, and reading the included leaflet I was supposed to run some dodgy BIOS update so it would charge.

My ass.

The battery has charged via the laptop, not only shows a full charge on the display but the laptop can operate solely on battery power. But you’re right, it is an aftermarket Chinese knockoff.

I am now suspecting the issue has nothing to do with the new battery installation. The laptop is getting old. I think it might be time to get a new laptop.