T61p won't turn on - blinking AC Power, orange Battery and Ultra Slim status lights

My T61p won't boot up. It's just sitting there with the AC Power light, orange Battery light (The battery light looks like it is being illuminated by both the green and orange LED at the same time) and Ultra Slim status light illuminated and they are blinking (so quickly turning off and then on - on for a second then off for a fraction of a second, etc.).
Even with the battery removed the orange battery light is on, and even with the charger disconnected the AC Power light is on.
I removed the keyboard and disconnected the motherboard backup battery, when doing so I noticed that the heatsink for the CPU etc. is slightly warm to the touch (not hot, but the CPU is obviously doing something as it's slightly warm).
When I disconnect the motherboard battery and try to start the unit, the same 3 lights flash, but now at a much slower pace and flash 4 times only. If I push the power button again they then continuously flash at a slower pace.
Any ideas?

 

Spoke to Lenovo this morning and they've got no idea, suspect the system board is faulty, but they can't confirm until they receive it. So it's going back under warranty (very glad to have gotten the 3 year extended warranty now).

 

Except that Lenovo will likely deny your claim, as you change the CPU yourself, while you're not supposed to (not a user replaceable unit). If they can somehow link the fact that you're using a non-supported CPU to motherboard failure, your warranty is as good as none.

 

I never did such a thing, of course it still has the original CPU in it. I mean who would send back a unit to do a warranty claim with a non-supported CPU installed? That would just be silly...

 

There may be a way for them to know that you change the CPU. Just be careful in putting back your original CPU is all I'm saying.