What would cause m6300 laptop to not even show bios boot?

Dell diagnosed the problem as a "bad motherboard," and of course it is just a few months out of warranty.

I replaced my motherboard with a used one from ebay. Still no signs of life.

Would a bad CPU, GPU, fan or something else cause the unit not to even show the BIOS startup? Power light comes on, but that's about it. Any suggestions on what to try/replace next to try to bring it back to life (I don't really want to buy a replacement GPU or CPU just to try it)?

 

Dell owned you.
Usually it is RAM problem or CPU sometimes. How much RAM modules U have? Try to use just one AND put it in different slots (if you do not know where is the first main slot). And turn laptop after every reinstalling a RAM to different slot or changing stick

 

Does it stay powered up? If it stays powered up, it's probably a GPU issue...

Problems with 8-Series GPU derivatives aren't as common in removable GPU models like the M6300 as they are in non-removable GPU models like the M1330, but it happens.

See if you can change the RAM amount and make it beep...

EDIT: You might just have a bad screen, too. Try an external display.

 

I don't think a bad GPU will cause it to not respond at all. Most likely CPU, although CPU problems can be indicated with flashing LEDs. Memory problems will cause lights or beeps.

Have you changed power sources (different battery or AC adapter)?

 

I did the memory dance before calling Dell. I might give that another go.

The power light stays on, with a slight hum from the top-right under the keyboard. I've been wondering if it is the fan attempting to start; quite possibly it has always done that. The DVD gets a brief jolt, but I can't hear anything from the hard drive.

Power supplies, docked or undocked makes no difference. Dell had me hit some key sequence that caused the screen to flash colors. I don't know if that is a sign that the GPU is still alive or not.

I was thinking that desktops I've worked on would sometimes refuse to go anywhere if the BIOS didn't sense that the CPU fan was operating. It could also be that my "new" used motherboard is just as dead as the first.

 

It depends on the system, some don't check the fan. Not sure about the M6300, but I suppose it wouldn't hurt to try to find another fan or get one from eBay.