Hi, i was purchased a northern brewer starter kit for christmas and brewed it over weekend, i followed the instructions and sterilised my equipment. So i'll go the through the process, collected 2.5 gallons of water started the heating process and added my grains to steep, removed after 20mins as instructed, brought to boil and removed from heat to add the syrup, mixed and returned to boil adding the hops as instructed, 60 min boil during which at 55 mins the hob turned off (stupid electric touch hob something brushed the control panel and it turned off) so turned it back on and put lid on the heat it back up for the remaining time, forgot the lid due to looking after child and it boiled over luckerly it had done its 60 mins so turned off cleaned up whilst the wort was chilling in the sink with cold water, lid on. Chilled it to below 100f as instructed. After the bucket was sterillised added 2 gallon of cold and added the wort, topped up to 5 gallon as the instructions say. Measured the gravity and its very low 1.020 should be 1.042, clearly something is wrong and i need help. Done some google searching to increase sg and if the calculation are correct its telling me i need at least 1kg of dry malt extract to up it...as i say beginner so open to all the help you have...please