Sony Vaio wont power up

ok basically i got this laptop for free off a friend who said if i can fix it i can keep it. I know nothing about this laptops history, however i noticed the power connector was broken, so this has been replaced.
Now it has power it will turn on but when i try to go into the bios it turns off.
I removed the fan and heat sink when i changed the connector but i'm pretty sure i fitted it correctly and cleaned it and used thermal compound so i dont think its getting too hot.
Still doing more testing but stuck right now....

Any thoughts :)