Dell Optiplex 9010 AIO wont power on fully.

Alright so normally I can fix any pc issue I come across but I have very little knowledge of AIO's

Client called me with a Optiplex 9010 All in one.

When plugged in the light next to power is green.

When you hit the power the power light goes blue and the  light above the power is white for 4 seconds.

Fan starts up for 1 second and nothing else happens. nothing on the screen at all  (normally)

sometimes when you push the power the fan starts for a second then dies then for the next few minutes it trys to start with fan going from 1 second then dead, fan for 2 seconds then dead, fan goes 10 seconds and then dead,  almost like a car engine not getting gas but trying to start up.

Whole time it does this the power light stays blue and the light next to the plug is green.

My guess is a bad capacitor on the mother board or a bad PSU.  This being a AIO I would have to order direct from dell or off ebay. 
So would like some more info being putting another $100 into a brick