*Skip to paragraph 5/6 for new solution*
My Laptop is an Acer TravelMate 5750G with 2x2Gb DDR3 1.3Ghz Ram, 1Tb SATA Hdd, Intel Core i7 Processor, Windows 7
It started cutting out about 5-2 seconds after power on. At first I saw the acer splash screen, later, it didn't even get this far. Pressing 'delete' to enter the bios didn't alter the time before it shutdown - I could see the bios screen momentarily, but after 5 seconds it powered off. Familiar symptoms?
I stripped the laptop down to parts (i.e. took it out of the case and booted it without peripherals - no wireless card, mouse, speakers, mice, USB sockets. Then I tried no HDD - booting from DVD, and vice-versa. I tried booting on battery only then AC only, swapping the ram out, reseating the cmos battery and even booting without keyboard and screen. In short I tried all the solutions other people had suggested elsewhere, even this:
- the 'Alt+F8' method. I didn't fancy bending the computer!
At this point the only things attached to the motherboard were the AC power jack/battery and a small piece of circuitboard that usually sits under the power button, which I had removed so that I could run the board outside the case. The symptoms were the same, so it stands to reason that there's a fault on either the main circuit board or the small power-button board.
So I looked over the circuit board under the power switch for any problems and there were several sets of about 4-8 parallel solder lines labelled jp1-4, (I guess that these are redundant jumper pins for alternative power button configurations by the motherboard manufacturer - there's space for a second power button and led on the other face of the small board).
I noticed that the solder between three lines of one set seemed squished and blurred between all three lines, so i used a screwdriver to scratch out the excess solder between the lines so that they were once more cleanly separated, tried booting it up (still out of the box) and presto! happily shunts its way to the ubuntu bootable disk connected!
I guess the power connector, loosely under the jumpers, got warm as the laptop warmed and exerted pressure on the solder, squishing them together. I have replaced the power socket on the laptop once already with an IR oven. After re-thermal-pasting and reassembly, the laptop booted into widows 7 from HDD normally, no problems.