Question Replaced Laptop Battery, Worked for a Day, now Won't POST

A friend's laptop wouldn't work a while back, it had been sitting up for a couple of years. I checked it out and was able to swap a battery from another laptop with the same model of battery (both HP). It worked so I ordered a replacement battery of the same model on Amazon. It was a cheaper one, cost $21 or so.

The laptop worked for me after the new battery when I tested it. I gave it back to my friend. They used it that day. The next day they went to turn it on and the keyboard will light up but the screen doesn't come on at all.

I hooked it up to a monitor but nothing comes up on the monitor either.

Fans come on and lights come one, caps-lock light is a slow-steady blinking. Wi-Fi light stays on and won't go off when the button is pressed.

If it's not something easily replaceable like HDD or RAM then idk what to do with it. It's old, maybe 2012.

Any ideas?