Dell Latitude C840 unable to power up without battery

my Dell Latitude C840 is a bit old and I was not used it for some time but today when I tried to use it , it won’t boot there was no led . now I am sure that the battery was dead but with the laptop's AC adapter plugged in it was flashing led light green 4 times then orange, then flashes orange 4 times and one time green, so I remove the battery anddecided to run the laptop with out the battery but it was not powering up the laptop . the adapter light was on . is there anyone here can help me on this I will be really be gald

The light are flashing that means that the battery is faulty but you already know that. And you will able to start the laptop without the battery with the AC adapter . may be the laptop has been damage check it with some technical guy .

I guess you might be need to remove the DC power board and reseating it again . I have see in some cases that have solve many battery and the power issue

Hey guys thank for the reply . I did what you have said reseated the DC power board but it is still not solve the issue. I am facing the same problem. Is it worth that I change the DC power board on my laptop, how much that will go to cost me.

Look like a power button issue to me or might be the mother board issue, I guess replacing the DC power board will not help you instead I suggest replace the entire motherboard and it is not that expensive. maybe something wrong with your laptop. Because u can start with no battery with ac adapter plugged in.

Look like you require a better power supply or you require to repair the system.

You might get this targus 180W universal power supply very cheap on eBay, that must be very much adequate. however that's just if your issue is because of the power supply.