Compaq 6175b won't turn on

Hello!
got today compaq 6175b that didnt turn on no lights came on. found out that in power supply comes 3 wires which are ground data an power, ground + data was 15v, and ground + power was 0v, so there was nothing on laptop when connected power supply. I cut down the wire from power supply to cord and fixed wireing of power supply showing corect ground + power 19v. now on laptop when connect power suply camoes on green light then changes to yellow and dissapers, and laptop still dont turn on. can it be some defence mechanism that knows that wireings is being cut down and prevents it from working? ? ? ? cant check if works from battery as dont have it. thinking if the damage is still in power supply or its something on mobo of laptop. so wondering if get new power supply or not as if its not power supply then there is mobo problem which I dont want to fix.

Sounds like a fried motherboard...

Just tried connect power supply to laptop and it on connect just turned on, but couldnt turn off with power button on laptop, disconecting power supply from laptop returns to same problem connecting power supply lights green light then yellow and no response.

Yes, the charging/power circuits on the motherboard are fried

Nope ! not in this case fixed! the dead thing was power on switch on mobo replaced it and I works like a charm now writing from my 6175b notebook

Good! Not a common failure though...

Yea true ! happy now! just found out one more problem but thats fixable too at the moment doesnt work left and right click buttons for touchpad will fix when get home from work