OEM battery, or third party?  And does the system recognize the battery (F2 at powerup to check)?

@ejn63​ yes its showing up on F2 and says excellent health but again when i tried to start up it shut down straight after the logo untill i plugged in the power lead

Was the system powering up with the original battery, or was it cutting out as well?

@ejn63​ yes it was and it was with the new battery too but lately it just doesnt want to start unless the lead is now attached its very strange especially when the battery has a full charge  

That means it's far more likely the mainboard is the issue - not the battery.