Inspiron 9300 will not turn on

Replace the system board.

The fact that the system won't POST and you've tried all the basic troubleshooting points to a board problem.  One last check would be to verify that the AC adapter is OK - the LED on it should be ON before you plug in the notebook end.  If it's not, the adapter is bad - replace it.  You should also check without the battery in the system  -- if the system will power up without but not with a battery, then the battery is bad.

If the AC adapter is OK but the system still won't POST, the problem is almost certainly with the system board.  If you've the skills and equipment to repair one of the thousands of cold solder joints on the board - go for it.  More likely, you'll wind up spending hours on a wild goose chase and have to replace the board in the end, anyway.  There are solder points all over the board through multiple layers - finding the bad one is like finding a needle in a haystack, as it were.

Why?  What could be wrong that I would need to replace the mother board?  I would consider replacing the mother board if I knew that that is the issue or if it is a bad solder joint I can fix it.  Can you tell me what the symptoms mean?  I forgot to mention that nothing else turns on beside the LED.

I was just doing some searching and came across a post from a few years back that had the exact same symptoms.  He replaced the motherboard and it had no effect.  I just don't want to be in the same "boat".  This evening I will most likely be pulling it apart and re-seating the cpu and gpu.  The charging brick is good as far as having the power LED on but I haven't checked the output with my DMM.  Could it be that the charger connector has broken loose, it hasn't been charging and it's just completely dead?  I notice that even when I have the charger plugged in it doesn't show that it is charging/charged but I don't know if my sympoms align with that theory

Thanks!  I will be trying it this evening.  I'll try to get back with details either late tonight or tomorrow.

Check the BIOS setup - F2 at powerup.  If the AC adapter is listed as "unknown", it could be a bad adapter, bad jack or bad mainboard.

I forgot this is the post:

www.techsupportforum.com/.../having-a-problem-turning-inspiron-9300-on-201631.html

Though the center pin is used in the adapter-detection circuit, even if it's bad, the system will power up (the battery just won't charge).

Unless there's an obviously damaged component near the power jack, the next step (assuming you can do it yourself - it's just not worth the cost to have it done professionally) is to replace the jack.  If that doesn't solve the problem, replace the mainboard.

I pulled everything apart, re-seated the cpu and gpu.  I checked the voltage coming into the motherboard and the center pin measured 2.57V and the middle ring measured around 19V.  I unplugged the charger and measured the plug.  The center pin doesn't have any voltage coming out. Should there be anything there?  I tried the F2 button but the computer doesn't get far enough to load the bios.  All that it does is turn on the power led for 5 sec.  The fans etc. do not get powered.

So, the issue is most likely the power jack/input circuitry?  I can definately replace the power jack.  I solder daily at my job.  I will be checking for a bad component.  What reasoning is behind pointing toward the power jack/ input circuitry?

Thanks for the help!  I purchased a replacement motherboard and got a better processor and video card to boot.