Renault Megane electric fault?

I have a 52 plate megane. A few days ago the oil light and stop light came on. I topped up with oil even though it didn't look like it needed doing as the dipstick showed the oil wasn't too low. The next day the battery was dead and car wouldn't start. I jump started it and drove for an hour to recharge the battery. Next day, battery dead again. I thought that something must be shorting and draining the battery. I jump started it again and left it running but it cut out and said there was an Auto Light Fault. When I tried to jump start it nothing happened and the fault said Electronic Fault. Now I can't start the car at all.
How can I reset the ECU? I have read about fuses/relays etc which I will try and clean but I need to know how to get around the electronic fault message to restart the car so I can get rid.
Can anyone help as I don't want to pay for a mobile mechanic unless I absolutely have to.