Hi, I can't recall how/why my laptop (Alienware) won't turn on due to the fact it's did not received power from its adapter, I've 2 adapters and both are working fine (they're both have green light on) I did remove the battery and plugged the adapter but still not working, before I do anything silly I wanted to ask how many possible issue outcome are there that's I have to deal with such as, is it battery? PSU? or the motherboard? Thank in advance.

Too early to say, ie it could be anything, even the Ram.

Have a look here: Tutorial: No POST (Power On System Test)

http://www.techspot.com/vb/topic55208.html

Possible dc jack socket where the charger plugs into is faulty. Very very common. Typicall costing around £75 + in the UK to replace at most good pc shops. But shop around you may get it done cheaper (or even for free if you know the right person )

Or possible other motherboard fault. Does it still power on or try to power on via battery even if very briefly?

The laptops does not received power from the source at all... (power adapter tested to be working) I am not sure if the battery gone bad could led to this problem since most of the time I've idle my laptop 24/7 while powered it's with adapter. or have the motherboard gone bad?

my guess is the motherboard 'went bad', which could just mean the traces around the dc jack have deteriorated. best bet is to pay to have it done unless you feel confident with your UN-soldering skills.

soldering it on is much much easier than removing it properly.