Before you power up the machine there are a couple of things you should check.

First open the back box, remove the back glass, and inpsect the main MPU board. this is the big board on the left side. In it's stock configuration, there should be a battery holder on the MPU board with three AA batteries in it. Most folks move these batteries off the MPU board into a remote battery holder. The reason is if the batteries start to leak, the alcali can do some serious damage to both the MPU board the driver board mounted under it. if the batteries are still on the MPU board, and they have leaked STOP here. Chances are the machine won't boot, and you are going to either get the boards repaired or replaced.

If the batteries are all good then verify all the fuses are the proper amperage, and none of them are blown. When you check the fuses, use a volt meter to verify you have continuity through the fuse, you can't depend on a visual inspection. Ive seen people try to substitute higher amperage fuses than the system is designed to use, and this can lead to very bad news if something goes wrong.

The fuses are as follows:

On the power supply from top to bottom:
F1 - HV .25A Slow Blow score Display
F3 - Lamp matrix - 8A Fast blow
F4 - Not used in Laser Cue
F2 - Solenoid 2.5 A Slow Blow
F5 and F6 Logic Power - 7A Slow Blow

The flipper board down below has a 5A slow blow fuse.

There are also 4 - 5 amp slow blow fuses on the side of backbox that are for the general illumination (GI).

If the fuses are all good, you are ready to try to power it up. If the games boots, chances are it will come up in audit mode (you will see a four or five digit number in the player 1 display, and no other controlled lights will come on). To get it out of audit mode and into game over mode, open the coin door, and quickly turn the machine off and on again. This should make the machine go into attract mode, and the controlled lights should start blinking.

Good Luck!