MQ500 won't power on

1 - Check the white reset button on the rear isn't stuck in - check when pressed you feel it click back out again. 

2 - Remove the 4 of hex fixings on the rear of the unit and gently slide out the rear panel - take care not to pull out quickly as some of the connectors inside are quite tight and damage can occur if pulled out all the way/forced out. 

check the white cable between the AC and DC card is securely fitted - unplug at both end and reseat. 
See attached here.

3 - Reseat the front panel connectors - see image 3a.jpg attached here. 
When doing this make sure the console is powered off and unplugged.