Hi team. I have a poorly macbook Pro. late 2011. It turns on, normal chime, normal fan, boots, then after about 15 seconds shuts itself down. What I have tried so far. Reset Pram Reset SMC tried from my other mac same year, different battery, hard drive, memory. Tried it with battery, or battery out with just power in. all the same result. However if i have no hard drive in, or no external bootable hard drive attached it stays on but obviously shows the flashing folder... ? as soon any drive put in and I've tried 2 drives, and 2 external bootable. shuts down after 15 seconds... umm stuck.. any ideas appreciated please.