My HP Pavilion ze4500 doesn't boot,how to fix it ?

Hi all i was trying to re install windows xp pro but my laptop hp ze4500 couldn't boot from cd rom!! so i had to use ctrl alt delete to restart the laptop a few time. Then i went to bios to check if the boot order is correct and i just changed the removable device to be 3th from that top(first boot cd rom ,second from hardrive ,third removable devices and fourth usb devices).

I saved the changes and re boot laptop but then i got a black screen and that black screen didn't go away for a while so i Press and hold the power button for at least 4 seconds until the display shut down.The i press the power button again but my laptop never turns on and i the logo screen doesn't appear!!(i think that damaged something)when i press the power button only keyboard status lights above the keyboard and one touch buttons turn on but the fan doesn't turn on and also Battery status light(AC power led/light indicator), hard drive activity light and power mode light doesn't turn on!!

I use universal AC power adapter to charge and power up my laptop. i tested it on my brother laptop and it was charging the battery so the AC power adapter is not faulty.I removed the hard drive and connected it to my desktop pc using a usb portable hard disk box and i backup my files so hard drive is not faulty either.

However the battery of my laptop usually keeping the laptop on for like 5 min at most when AC power adapter was not used .Therefore, most of the time i was using AC power adapter.

So do you think guys the battery is causing this problem ?
Getting new battery might solve the problem?
Do you guys think BIOS got damaged for some reason ?
If motherboard needs replaced how much probably it cost and where to get it?

Also i am wondering why the Battery status light doesn't turn on when AC power adapter is used?

I be happy if you guys tell me what exactly went wrong and is it possible to fix it? Looking forward for replies.Thanks

Note: see the attached pic of laptop main status lights