asusk43sj Laptop boot loop, cannot access BIOS

[turquato]

Hi!

 

A bit of a back story
So recently I was given a ASUS K43S (K43SJ) to tear apart by a friend to get the hard disk. This laptop was missing its battery and power adapter so I was not able to test it immediately but it was supposedly working.

I went to a computer store and was hoping to purchase an adapter for the laptop. Upon arriving I asked the store owner if I could test the laptop and the power adapter if either one works but unfortunately, the laptop did not exhibit any indication that it was receiving any power from the adapter. So now the obvious option is to find a battery pack, which I did, and unfortunately still no sign of life from the laptop so I held up on the purchase of both battery and power adapter. I got stuck for days and weeks thinking what I could do to give it life. Then I found a power adapter which unfortunately did not have the correct fit for the laptop.

 

Modified Adapter

So I cut off the wire of the adapter (19volts forgot AMPS) and soldered the positive and negative directly to the laptop motherboard and lo and behold....lights and fans started working (hurray!!!)

 

A success short lived

After I seeing that what I did was somehow powering the laptop, I felt confident, pumped up even to proceed with testing. And when it POSTed it showed me the press F2 to enter setup and F4 for BBS Popups and about 5 seconds after pressing either of them, the laptop turns off, cycles back on with the CAPSLOCK LED ON and a black screen.
 

Quick Summary

A ASUS K43SJ laptop with no hard disk, no battery and missing a power adapter.

Tested with new battery and power adapter but did not power on.

Modified a power adapter directly soldered to the board.

Laptop turns on but cannot enter BIOS then turns off, then on and stuck on a black screen.

 

Other things done

I have removed the CMOS Battery (this allowed me to see the BIOS prompt every time before switching off. If I don't remove this, I'm always stuck on a black screen. Also changed with new one.), pressed and held on to the power button for quite a while (to drain power from capacitors)

Queries

Is there any other way to access the BIOS?

What other methods of troubleshooting should be done?

 

Any bit of help is appreciated.