After removing all the screws from the bottom of the laptop I removed the keyboard and could immediately see signs of what the issue might be..
..water damage!
Depending on what damage has been done it may be fixable so lets take a look...
No obvious signs here and after having a good look around I cannot see any more signs of liquid damage.
Using my Digital Multimeter I checked the power supplies on the motherboard and was able to find the 19.5V, 3.3V, 1.2V and 5V supplies at all the coils I could see so everything seems OK.
Time to remove the heatsink to see if there's any signs of damage under that.
And there we have it - water damage around the CPU and GPU. As the laptop is not powering on (not getting the power good signal to start the CPU etc) it's likely that the GPU is what is at fault.
Time to get my thermal camera out and take a look to see if anything is getting hot/shorted out when it shouldn't be.
The CPU is on the left (nice and cool as the laptop has not been turned on) and the GPU on the right is glowing like the sun! As the laptop is powered off this shouldn't be happening so it is my belief that the GPU is faulty/short-circuited.
Time to get out my USB microscope to take a closer look at the GPU:
As you can see there's a sticky, hairy mess all over the ATI GPU so 100% certain that this is the problem area.
I don't have the skills (or a spare GPU chip for that matter) to remove/replace this IC and as the water damage goes towards the CPU socket as well the CPU may also be faulty/shorted so it's not worth the time/effort to repair.
I will keep the motherboard for spares and repairs in case I need any of the other components to repair any other laptops in the future.
You can't win them all!