Help me please!

[Mikeash609]

I got my Nexus 7 yesterday and I'm panicking that I've broken it already. I Rooted it as soon as I got it and had no problems. I then tried to put Cyanogen mod 10 on and it went wrong, it just cycled the logo at the reboot and that was it. I went on and managed to fix it but I didn't like it so I tried changing back to jelly bean I found the Jelly bean rom online that I wanted and got it going then I started to redownload my apps and it told me to update it so I did it then went to the recovery bit and I tried to install what I assumed was the update. Basically my nexus is stuck on the Nexus logo on the reboot and when I try to take it to recovery it has a picture of the android with his chest open and a bright red "!". Please can someone help me, this is my first android product so talk to me as if I am five.