Mac Mini (late 2012) No boot, heavy fans after upgrade Not sure where else to turn - just upgraded two Mac Mini (late 2012 models) to include 120GB SSDs. 

The first one went fine - took the update and booted properly. Great.

Second one, after closing the case, connecting power and turning on, I get the power light and the fan progressively spins up until it is running like crazy. No beep, chime, or screen output. I tried putting the old hard drive back, but same behaviour.

I double checked every connection both before and after the problem so I'm pretty sure that's not it. My gut says I shorted the logic board (possible) - has anyone any experience with this or these symptoms? I have worked through Mac will not boot, and no display output.

Thanks in advance!
Were you ASD safe? If not there is a good possibility you had some static discharge that shorted the board or the memory. 

Actions to take:
Does it let you reset PRAM?
Try unplugging the Mac mini and holding the power button down for 10 sec. Apple and others may say you do not need to hold the power button down but I have found with some models or issues it help.

Check to see if HDD sensor is shorted/damaged.
If none of this works the you will need to start part isolation or bring it to someone who can. 
i.e.
Take out the RAM and see if you get an error beep. 

Good luck.