Help! Car is dead!

[CDS-GT]

So i have my 2005 Legacy GT wagon, limited edition. I got to drive it for all of 6 days when some lady ran an intersection and smashed up my front bumper/hood pretty good. So its been sitting for a few months, however the battery in it was working just fine before the accident and even when i drove it home it still would start. However I just put a brand new battery in it and checked the alternator, everything is good and working. It started up the first time barely... Then after letting it run for only a couple minutes I killed the engine and waited to start her up again, when i turned the key over i get my lights and all my dash is working, but it will NOT crank over. Completely dead with a new battery and only started once. Please if anyone knows whats up ?? I'm trying to get this car in a shop and fixed up soon.