Mass closure ??

Hello people, I’m new here and that’s not without reason. I drive a 92’er omega A, 2.0 CD sport, automatic. I love this car!… unfortunately I have the following problem, if I turn the ignition key to start the engine, the power supply collapses, the boardcomuter shows only strokes, the radio loses the code, the starter doesn’t spin at all and the zv tries to close quietly. also the automatic transmission makes grinding noises, at least a two times, at incha Letter ignition. I drove the car normally today, turned it off for about 20 minutes, and then wanted to go again, ratze, from now on on nothing more. the days I had the following problem, during the ride, suddenly the amature lighting went out and the flasher lights and the remote light lamp lit up, speed meter, fuel meter and temperature indicator, everything was dead…after a short time it was then again…maybe it was connected with it? oh yes, if the ignition is on, also only a short time, the minuspole on the battery gets quite warm…. can anyone tell me what this is??? mfg. hausi