power issues...maybe powerjack? motherboard?

Working on agateway md2614u laptop thats having power issues.

When i plug in charger i get a yellow blinking light.If i let it charge overnight i can get it to boot up for about two minutes and then it shuts down.

Also wont start without battery.

I have bought new battery and charger for it. Have reset ram and checked ram slots. drained battery several times. Also reseated the cpu.

No fan or heating issues.

I checked the power jack and it looks fine. no bent pins. no burning signs on motherboard.

sotter on powerjack looks good. but i may install a new one anyway.

im guessing that its not the motherboard since i can get it to start up sometimes but only for a few minutes? not sure...

I wanted to update bios but cant get computer to stay on long enough and don't want it to turn of in the middle of it.

Also wanted to update any drivers that have to do with battery or power. Any ideas at all before i put a few bullets into it?

Would a docking station help? (not sure if is even capable)