BGA reflow issues while fixing an old gaming laptop

In my experience, trying to learn soldering for component repair has been tough but interesting. Your mileage may vary, but I picked up a basic iron and some boards from broken machines to practice. Take this with a grain of salt, I successfully fixed a few loose ports on a buddy's laptop. Now, I'm stuck on a BGA chip that refuses to reflow correctly on an older gaming rig. I suspect my heat gun isn't powerful enough or I'm applying heat wrong. Has anyone faced similar problems with BGA work? I'd appreciate any advice on good temperature ranges or handy tricks. Also, what basic tools should I look for next as I dive deeper into this?