Laptop not turning on even after replacing motherboard

[assafelbaz]

Hi.

I have HP Probook 4510s that been not working for a while. I decided to check it and i found that the power supply is good (tested with multimeter) so the motherboard has to be replaced.

I ordered a new one and i connected the CPU, RAM, screen and power jack. The light on the power jack was off. No power, no fan, no lights, same as the old motherboard.

The power jack has been a bit old so i thought maybe it is the problem so i ordered a new one.
This one acting the same as the old one.

After contacting the supplier he sent me a new one. This one acting the same as the previous 2.

I tried to push the cable plug strong toward the power jack and it is turning blue for half a second and then amber for about a second and off.

I also checked the power jack for voltage, it indicates 19.96V.

Do i miss something? Maybe i should build it in full to check it, not only screen, RAM, etc...?
Is it possible that the power jack (the second) also not good?

PLEASE HELP!!!

[Dr_Bob]

My guess is a failing/bad AC adapter. Sounds like the Head of the AC adapter may be loose, hence being able to push hard and it get a LED on the DC jack. Try borrowing an AC adapter from a friend or a local PC store to see if it works. I know you can get them off of eBay fairly cheap as well.