L645D-S4037 No Boot

This laptop was my moms, and she gave it to me after it died and only came up with the black screen. I have tried holding the power button with the battery removed in multiple time sequences with no luck. I just
Received the new motherboard in the mail, put it and damn it did the same thing. I have tried booting it up with he cdrom and HDD out, disconnected the wifi card, swap and removed the ram chip
and still no boot and the black screen. It sound like it's not posting. My next assumption is that the CPU had died, but hate to purchase that if it's something simple i missed. Please Help!

 

Addition to the original post; the compound on the CPU was completely crumbling and easily removed. I found this unusual; I also heard that AMD do fail.

 

In addition to this post, I have decided to order a replacement AMD CPU, hopefully it will be here by the end of the week. I will keep all up-to-date if this fixes the issue of No Post!

 

I think your confusing GPU failure to CPU failures to very different components... AMD GPU had more failure rates because of their selling bad GPU. But before ordering a new CPU did you redo the thermal paste on both the CPU and GPU and see if it still powers up before buying a new CPU???

 

Stormjumper, many thanks for jumping in here, I guess the possibly exist that the replacement MB I received is also bad. The only reason I ordered a new CPU, one it's, 1.9 Ghz instead of 1.8 Ghz, and I wanted to rule out the possibility of a bad CPU. I may try to reflux the original MB around the GPU. I have done this before on HP Mobile MB and have had some luck. I have never tried to do a Toshiba MB before. I may just go ahead and send the board I ordered back to the seller.

 

OMG, used a heat gun on the orignal MB GPU only, for only 1 minute, put the old and sure enough the **** thing fired right up! for how long I will keep this thread going with updates!