You need a keyboard. There are diagnostic lights to the left of the RAM slots, open it up and try to start it and let us know the status of the LEDs.
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You need a keyboard. There are diagnostic lights to the left of the RAM slots, open it up and try to start it and let us know the status of the LEDs. Use this guide as a start to get into it: http://www.ifixit.com/Guide/Repair/Installing-iMac-Intel-21-5-Inch-Power-Supply/1771/1