when transporting games, especially ones that have changed hands probably more than a few times, you have to check over the various connections inside the machine. I'm feeling kinda wordy right now:
JAMMA harness: this is the black connector that plugs into your game board. every input (such as your coin switches, your joysticks, and in the case of MK, the top 3 buttons, etc.), every output (such as the video signal that goes to your monitor, the sounds that play through the speakers, and on a very minimalistic level, the coin counters), and all the power wiring that comes off the power supply (for MK, this is +5V, +12V, -5V and of course the ground wires)
JAMMA harnesses usually go on pretty tight, but for the hell of it make sure that's on pretty good.
power supply: the power supply is powered by the 110-120V AC (your mileage may vary) feed that comes out of your wall outlet, and turns that into the various voltages I outlined above. MK uses a switching power supply (as opposed to what you'd find in a Pac-Man, Galaga, etc. -- those use linear power supplies, meaning they just have giant power supply boards set up to provide voltages). switching power supplies have a +5V adjustment knob on them, this is done because different games have different power needs. games with larger sets of interlocking boards for instance will need the power supply's +5V to be set a little higher to ensure that the game's getting a little bit over 5.05V to the circuitry -- if this is too low, then the game will malfunction. this is exhibited by a number of different factors, such as the game freezing up mid-play, or the graphics scrambling, or potentially in your case, not powering up at all. UNDERvoltage can be just as bad as OVERvoltage if you continue running the game under those conditions.
getting back on topic with MK though, MK has 2 boards: the main board, and a sound board. the sound board piggybacks its power off the main board, so generally I like getting about 5.10V at the JAMMA edge. if you know a thing or two about a digital voltmeter, it'd probably be in your best interest to check the +5 terminal to see what kind of +5 voltage you're getting at the power supply itself.
a thing to note about switching power supplies: only the +5V is regulated (via that adjustment pot) -- all the other voltages are "created" based on what you have +5 set at. it's not uncommon for the +12V for instance to run about 13.60V.

also, under no circumstance in a working power supply will you ever have any other voltage besides +5 and have no +5.
that's enough about those.
the monitor: dedicated MK cabs shipped with isolation transformers, considering your monitor's turning on and all you're seeing is a white line, and the monitor didn't go KABOOM, I'm going to assume that you're getting 110-120VAC to it from the proper wiring to the iso. the other thing to check for is the video signal, which the actual connector's appearance varies from monitor to monitor, but what gets carried through this is the RGB signal (red, green, and blue are separated), a video ground, and then a video sync (MK uses what's called "composite sync", meaning the horizontal and vertical sync signals for the monitor are combined into one -- older games had them separate.) if under any circumstance your monitor (as in, the actual CRT tube) sounds like it comes on, and the glass neckboard is glowing an orange-like color (which now that I think about it, I don't think you can even see this in a MK/Midway cab!), and you can hear the game playing sounds, but you have a blank black screen, then it's most likely that your monitor is not receiving a video signal.
so.... I doubt the power supply would die mid-trip, my best guess is you should check the JAMMA harness that it's seated in good and tight. if that wasn't the problem, then next plan of attack should be the power supply -- perhaps a connection came loose (I'm going to assume this uses a screw terminal power supply, if it isn't, let us know!). actually, easiest approach would be to see if the power supply does in fact have an LED on it to see that it's even getting juice.
and welcome to this sadistic hobby!
