Dell Vostro 220 power up issues

Hi,

We have a Dell Vostro 220 which is having problems powering up.  It began intermittently but now it very rarely powers up.

The green light on the back where the power cable goes in is lit.

When I push the power switch, it blinks amber once. Then both fans start, but stop after a second. Then they both start again, for less than one second. The power switch blinks amber once more. Then nothing. In the past we could try again and it would start, then it got worse and we would need to repeat 10 or 20 times to get it to work.  Now it seems we could try all day and it would never start.

I opened it up. Disconnected and re-connected everything and tried again - it worked fine. But next day it wouldn't power up again.  So I opened up and again, and this time I changed the CMOS battery. I power it up 3 times in a row and it worked fine, and the user used it for the rest of the day.

However, this morning, it refused to start up again. Same problem as before.

Is there anything else I could try ?

Thanks very much,

Peter.