The ECM could have died in 3 months, repro pattern parts are rubbish.
It is a 1984, so has it been Nuttered or is it still run by the computer? If so, is the IGN LPS fuse working? This little bitty fuse can knock out the ignition as the CEC computer filters and alters the signal from the pickup in the distributor before it gets to the ECM. No fuse, no voltage, no computer = no spark. I attach a fuse box diagram.
The battery terminal arcing is because it is worn out / corroded / loose. You need to take it apart and clean it up and fix it. This will turn the gauges on and off.
The carb flooding could be completely unrelated. If it is a BBD, when was the last time you took the top off and checked the float levels and inlet valve? It is a 10 minute job when you know what you are doing. It will run without the top on, allowing you to check the valve is topping the flow and the float is preventing excessive petrol levels in the carb, the main causes of flooding. If you have an electric pump, it could be doing it without cranking. If it is just a choke issue then you need to set up the choke mechanism, see Jeephammer's old posts.
The thing to check though is the ignition for spark. Take off one of the spark plug leads and put an old spark plug in there and hold it on to the block. Get a buddy to swing the engine, is there a crisp regular spark?? If not follow it back to the coil to check for spark.
If you are getting no spark break out a 12V test bulb and some long leads. Hook one end to the battery negative. In Run does it glow dimly when connected to the coil positive (red with tracer)? In Start does it become Bright?
If you hav evoltag eta the coil disconnect the light green wore from the other side of the coil. Hook the etst bulb between this and the battery positive. Swing the engine, does it blink on and off?
BagusJeep lives in Bali, the Land of Temples.
With a Jeep every prayer counts.
1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
1995 Cherokee 4.0 - CHEROKEE