Replaced bad caps and still got problems...

hi ,
I've replaced all 25 bad capacators on my i mac g5 i had them done through a professional electronics company so know the work was done correctly.
However when i came to start it up for the first time (and everytime since)
i get the grey apple logo and spinning icon
can hear the disc drive test? can hear the fans .
And then the whole thing just closes down.(within a minute or so)
If i try starting with startup disc it does the same thing.
If i try starting with 'ctrl r p' i get a kernal panic? (black dialogue box telling me to re start)
Just before it broke on me i had sign in issues where i had to type in a command to re set my password.(black screen)
also did the led check with the back off and all was ok .
has anyone any ideas please?
much appreciated.

Was the electronics repair place an authorized Mac repair service center? Did they check out your machine after the repair was done? Take it back to them.

Regards.

Try starting with 'ctrl r p' i get a kernal panic? (black dialogue box telling me to re start)

If you mean by this you tried to zap the PRAM, it is done by holding down Control, Option, P and R keys all at the same time immediately after the chime.

How to Zap PRAM on a MAC | eHow.com

Further to Harry's advice, I suggest you check out the status and condition of the physical RAM. Something might have been messed about in there when the capacitor replacement was being done.