Fryed ECU in 1992 4Cyl TR Mitsubishi Magna when changing down gear. Changed ECU for a good one but the engine only turns over now and will not start. Checked everything but still cant find problem.?

Have you checked the fuse for the ECU? I'm unfamiliar with your specific vehicle, but this fuse is ussually located under the hood in a fuse box. Normally the manual will help you track down the location of all the fuses. If its not the fuse, perhaps there is a ground somewhere. Be sure there is not another fuse that may have blown when you fried the ECU.