Dead M6811

So here's my dilemma:

I was handed an eMachines M6811 yesterday that will not power on. Since it's off warranty, I can't really send it in without expecting to pay an arm and a leg for it, regardless of the fact that I don't know what's wrong with it. It's one of those "You fix it, you keep it" sort of deals. So I'm trying to save it from being parted out without breaking the bank on it.

Symptoms:
When you hit the power button, it does nothing. When plugged in, the external power plug LED below the touchpad keys does not come on.

So far, I've just opened it a little and checked to see that the cables were connected (they were). I have a working M6810 so I've tested it with my own battery and my AC power brick and it's still 100% unresponsive. The previous owner told me that once, before it went completely dead, he was able to get it to turn back on and boot up fine by taking out the RAM then putting it back it. I don't see how that's at all relavant as a mobo should still turn on with fans spinning even if only one RAM stick in there. I've powered in on with and without the accessable DIMM in and nothing.

Most people would say that it is the power plug in the mobo and to look for a broken solder point. I actually had this problem with the M6810 and was able to send it in to be repaired (as well as the AC power brick and cracked hinges). Anyhow, I've tried it with the battery from my M6810 which I know for a fact is fully functional, and it still doesn't power on, or do anything for that matter.

I've tried the RAM and HDD from my machine too --you know, just in case-- but to no avail.

So I'm kind of at a loss. I tried a few things to eliminate the possibilities as to what could be wrong, but perhaps I'm looking at the wrong thing? Before I totally gut this thing, I'd like to see what the gurus on this borad can make of it. So if anyone could shed a bit of light on my predicament, I'd really appreciate it.

qhn: Firstly, thanks for the quick reply. I see you all over these boards being one of the most helpful people. Now, in regard to the checklist:

1. Well, I've tried the Battery and Brick switch; those parts seem to work just fine.

2. Same thing with the RAM swap. The RAM from the M6811 is currently in my M6810 and is running smoothly. I didn't get a chance to run the memtests on it but with my working RAM in there now, I'm pretty certain that's not it.

3. I'll have to try the CPU tonight. With the process of elimination, it's a 50% it's the CPU. The fact that the LED doesn't come on when it's plugged in, (blue and orange LEDs on the front as well as the plug icon) lowers that possibility quite significantly in my mind. Referring back to point 1., the Batteries and Bricks are all functional so some light or indication that it's being powered would be apparent. Point 2. is irrelevant seeing as how volatile memory needs power to work as this isn't a boot problem but a powering issue. I'm not ruling out the CPU, but my old desktop would power up and go to BIOS without a CPU in; I'm not sure if that's true of laptop mobos though.

I've more or less narrowed it down to the fact that it is infact the mobo. I'm more looking to see if any of you have shared this problem, found any meaningful resolutions, or have an suggestions as to what to look for if it's at all possible to even diagnose the problem with the given symptoms. Again, any(more) advice would be great. Thanks.

Thanks for the advice, guys. I'll follow it tonight and/or this weekend and post any resolution I come to for other members experiencing similar problems.

I was also thinking it could be a short but just didn't know where to look. I'll check for any short circuits on connectors and on the board itself and do a CPU swap just to be safe afterwards. Any other words of wisdom before I gut this thing?

Update: Okay, it turns out that my mobo is dead. I don't know how, but it is.

I first disassembled everything carefully, and checked both sides of the board with a magnifying glass for any cracks, chips, singe marks, borken solder points, corrosion, stains, and found nothing. It's actually cleaner than the board I have in the working M6810. If there is no problem that was identifiable visually, I don't see how it could be fixed. If it's a problem within one of the layers in the actual PCB, there's no way of knowing or separating them without destroying the board entirely.

At this point I plug everything back in with great attention to the cables and how the plugs are seated in the pins, hoping that maybe it was a short. It wasn't. I tried powering up again and got the same result. Nada.

Hoping against hope, I swap the CPU (3400+) with my M6810's (3200+) and the 3400+ checks in both BIOS and windows. Looks like it's running fine. So it's obviously not the chip. Just in case, I tried my 3200+ in the M6811, and nothing. Of course.

So it's pretty conclusive, the mobo is officially dead unless someone can suggest something that I may have missed and should be checking for, perhaps? I'm sorry for all the other members having the same problem. I know it's no solution to say, "Buy a new mobo" or "Return it to Best Buy" because that's not what you read these forums for. I wish I'd been able to come to a resolution that didn't require one of those two options. I for one will be getting a new mobo and trying to revive this thing. I lose, haha. I hope any one else sharing this problem may have better luck than me.

On a lighter note, I used to have extreme heating issues with my M6810. The left palmrest would get extremely hot and so would the bottom of the unit. In the course of disassembling both machines multiple times, I cleaned off the old (stock) thermal compound and liberally reapplied some Arctic Silver 5 rather liberally and it seems to have alleviated this problem altogether. It still gets hot, but not too hot. Who ever heard of a laptop that was too hot to place on your lap? In any case, no need for extreme mods there. Just a reapplication should work well enough.

Good Luck, all.