I have an Inspiron 1745 and as of today it will not power on completely. When you push the power button the light on the button will come on and the computer will sound like its going to start then immediately shuts off within a second. The ac adapter works fine battery is fine. I took the backplate off and removed the battery and pressed power button for 60 seconds and it still does the same thing. I am thinking based on some other similar posts that the computer is "stuck" in sleep mode or something like it thinks that the lid is closed when its not. I tried pressing the power button while pressing FN and it does the same exact thing. I did try the BIST test and that works (no abnormalities that I can see) and when it goes to restart it immediately shuts off. I do have an old external monitor but there is no place to plug it in because it does not have an HDMI cable and this computer has no ports besides usb and hdmi. I am not tech savvy enough to figure this one out on my own.
Unplug the system, remove the battery and hold the power button for 30 sec.
Remove and reinstall both memory modules and the hard drive.
Try powering up on AC only. If you still get the same fault, try one memory module at a time in each socket until you isolate the bad module or socket. If one of the modules is bad, replace it; if one socket is bad, replace the mainboard.
If the system will power up on AC but not with the battery, the battery is bad - replace it.
If the system still won't completely power up after doing the above procedure, the mainboard is bad; replace it.
You have an 8 year old laptop. If you find any problems after running the tests or if you cannot run any tests, replace it with a new computer. Eight years is an excellent run for a laptop and you would be wasting money buying any replacement parts.