It appears to be a coil/capacitor magnetic ballast, not electronic. In most cases with these, it's the capacitor or ignitor (if it has one) that will fail. Either should be simple to replace, but you need to get the numbers/specs of the capacitor in order to find a compatible replacement or original part. Careful when handling a capacitor, particularly a large one, they can store a charge for a long time. Short the terminals with a screwdriver or something similar with an insulated handle to discharge it. If you put your fingers across the terminals inadvertantly, you could get a nasty zap.
I see that you've purchased an LED fixture now, but it may still be worth resurrecting the Halide. A couple of links to pages with pdf version of HID Lighting Ballast Pocket Guide follow. This has detailed info on most types of ballast & includes a troubleshooting section at the end.
http://www1.eere.energy.gov/building...ance_2003a.pdf
http://code-elec.com/content/00/01/5...ting-guide.pdf
& a link to the manual for your light, I think...
http://www.aquacave.com/Manuals/JBJ-...luxeManual.pdf