New question,old issue- comp does nothing

good afternoon masters of the electron
i am at work at the moment and shall post back with more specific system stats ,but heres the story..........

a friend gave me an old computer that worked intermitently and me,being just smart enough to get in trouble,opened it up and started feeling around a bit. i took the cpu (athlon xp 2600) and upgraded another system, no problem there. i then installed an amd duron 1.6 ghz into the system and it did boot fine. i installed a larger hd(maxtor 40 g) with xp installed on it and still no problem. now here's where the plot thickens.....
one of the 4-wire hd connectors was ty-wraped to the 6-wire front panel harness. this would not let that connector reach the hard drive bay comfortably, so i snipped the ty-wrap with small side cutters. now, in the process of pulling the 2 harness's , the 4 mobo/fnt. panel connectors came off the mobo.

i looked up the mobo manual on the net and found the diagram for the fnt. panel riser and reconnected the 4 2-pin conections.
after that nothing..............

no post, no fans, no leds,no sounds/beeps,and no sparks

i have checked the obvious ,power cable from wall,little switch on the backof the power supply ,the 110/220 red sw. .
i have tried stripping down to just cpu,ram,hd,video card and still nothing
i read on this wonderful site i could try nothing but cpu,and ram to verify psu,
but i've never done that. i have tried another power sw from a good known case (i think its good).i have tried the old butter knife jumper to the 2 pins on the mobo ,and i tried cussing like my mother-in-law.

my next option would be to remove the psu from my best system to try on this one ,but im reluctant to do it. i have many other psu's i could try yet none have the 4-pin mobo connector as this system does.

i would like to try any ideas you kind people might have before i start throwing cash.

i should add i tried the j1 board reset and removing the bios/cmos battery
you guessed it ;;; nothing

thank you for your time in reading this ,and i shall watch for any replies

mikey the Mad

Was it turned on when the cables came apart?

greetings...

no the system was powered down at the time.
last night ,i tried again and removed everything of the mobo,including the cpu,ram and all connections. i reinstalled the cpu,ram,2 power groups to the mobo and the 4 fnt panel connections.
pushed power on and (viola!!)

now i get a green light on the front for abous 1-2 secs.cpu fan spins untill i power down.

i added hd and video card and the hd is spinning, yet no video out and still no beeps.

acts like psu huh?????
also, if this is a mobo issue, can it damage a new psu???
i can try another one from a working system but i won't if theres a danger of damage to the good psu

the mobo is an ecs nu2-400-a
i have various parts to make a nice system but cannot if it wont boot stabely

once again , thank you all for your time and responce

mikey the Mad