Car has had some electrical issues

Car has had some electrical issues. Recently cruise control, gag gage stopped working. Battery was old and weak. Ran out of gas (my son forgot to tell me no gas gage), Drained battery trying to restart. Replaced battery, added can of heet and 5.5 gallons of fuel. Tried to start with no success. Battery was starting to get tired so hooked up my chrysler pacifica. Tried to start a couple more times and on the third attempt lost everything. No dash lights, nothing. Not even a click when I turned the key. Some one has suggested that the main relay is likely gone. Help?