The orange light means that the monitor can't detect video output from the computer. There are a GANG of reasons this can happen, but there are some fairly common ones associated with moving and storing computers, and RE that, here's some stuff to try:

(1) test to see if the computer is actually booting or not: power up the system and see if it goes through all the normal startup things (the floppy drive whirrs, the hard drive is busy for amout a minute, and then everything is quiet). If this stuff does happen, try pressing CTRL-ALT-DEL and see if it re-starts and does the same stuff. If it does, and you don't hear a lot of beeps, the liklihood is the monitor, video card, or monitor cable is the problem.

(1) If you hear hear a 'beeeep beep-beep' when the posers up the system, this can indicate a video incompatibility problem, which CAN actually be a bad connection problem.

(2) if the monitor connector is a 9-pin DIN, make sure the monitor cable is plugged into the monitor port: Some older (CGA/EGA) monitors can plug into a 9-pin port, like a mouse port. This NEVER works.

(3) If the monitor is a 15-pin DIN (vga/xvga), or you are just dead sure you've got it plugged in right, the next thing to do is see if moving the computer has joggled the board loose, or if during storage, the video card contacts have oxidised (did your brother store it in a garage, or someplace damp?). The best way to do this is to remove and re-install the video card. THis tends to re-scrub the slot connections and re-establish electrical contact.

(4) check for obvious kinks ir fraying of the Video cable, and disconnect and reconnect the monitor cable. If it can be disconnected from the monitor, disconnect and re-connect it there, too.

If you STILL see an orange (no video signal) light from the monitor, you should then consider calling a professional, or buttonholing a techie and having him/her/it check the system more thoroughly.