New PSU, more problems...

[theares405]

So i had left my PC on when i left the room for a few minutes, i came back to a pop and smoke coming from my PC, it turned off and wouldnt come back on, i figured it was a faulty PSU, i had just installed it about 3 months prior to this. I just bought a new PSU and installed it and i went to plus it in and the PC was instantly on, the fans were spinning, the lights were on but nobody was home.. No display and everything is spinning hard, i pressed and held the power button but no response, i have to shut the PSU off in order to stop the PC.. Im lost.. Please help..

Update: messed with some cables, jiggled some around and got the PC to start up so i know the mobo, gpu, ram and pcu are fine but the power button isnt responding, i held it in and nothing, not sure if its a loose wire or what, the led is working but not the button. Unsure as to whats going on.

Edit:
CPU: Phenom X4 9650
Motherboard: MS-7548 (Aspen)
Ram: Not sure, came stock like everything else. 8 GB DDR2
SSD/HDD: WD Blue 1Tb
GPU: ATI Radeon HD4350
PSU: EVGA 650W
Chassis: HP Pavilion midsize ATX
OS: Windows 10
The old PSU was a crappy Thermaltake 430w.

 

[Lutfij]

1| When posting a thread of troubleshooting nature it's customary to include your full system's specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
PSU:
Chassis:
OS:


2| We'll also need to know the make and model of the previous PSU.

3| You might also need to breadboard the system and prior to assembling outside the chassis, might want to also inspect if any area on your components have brown patches or swollen capacitors.