power supply noob help

Hey there everyone,
Finished my prusa i3 mk2 build late last night and ran into an issue with the hotbed motor being constantly on, unplugged and went to bed with the intention of coming back to it this morning.
plugged it in and nothing. The lcd screen isn't giving me a menu option any more and the power-pack fan isn't activating either...help!

If the " hotbed motor" is the Y-stepper and you unplugged the stepper from the controller, while it was powered, you might have killed the stepper driver and more...
What happens without the Y-stepper driver inserted and a USB connection? Maybe it works with 5V supply over USB, then the Arduino onboard regulator is dead.

that wont explain the power supply giving out though would it? and I'm not getting anything, Over usb I have lights activating on the stop switches and lcd board but like I said no menu option.
I unplugged from the mains supply not the board

Starting with the easy stuff...

Looks like the Prusa i3 Mk2 uses the RAMBo mini card looking at the Pruas website, would that be correct?
Looking at the card, there appear to be three plug in fuses, 2 x 5A and 1 x 15A. Have you checked them?
If this is the correct card, it looks like your motor driver chips are built in to the board and not add on daughter boards so if one was blown you'd need a complete new card.

I've got a different printer but when powered on the PSU led lights up, does yours work this way? There could be a blown fuse in the PSU.
Have you got a meter you could use to check the voltages from the PSU?

Have you checked there is mains coming from your power socket, have you tried a different power cable. Is there mains voltage at the end of the power cable?

Sorry if these checks sound simple and stupid but I've been caught out before by diving deep into a problem without checking the basics and looking foolish when the piece of kit wasn't plugged in properly or something.

IBM faultfinding MAPs always start with the silly stuff like this.

Play Bonny!

Soadyheid.