Car wont start (no power)

Hey people. I got back from a little 3 day vacation yesterday to find my car has absolutley no electricity running through it. So it hadn't been running for approximately 2 whole days. I tried to jump start it w/ my moms car, but even though power is running through the car(radio, clock, lights, etc. are on) now it will only stutter once (really short too) and not turn over.

I had this problem a little while ago, but it turned out to be poorly connected battery terminals after trying to install a remote start system. So all I had to do was tighten them down and problem solved. So when this happened I checked to see if the terminals had somehow become loose, which they haven't.

So now I'm thinking that the cause of power loss may be from the wires used for the remote start. I had already completely uninstalled the system a while ago because I decided I didn't want it. Also, originally we weren't able to get through the firewall so we tapped into an alternate power source under the dash. Perhaps I'm losing power through there? But I completely taped up the wire with electrical tape.

Finally, the battery is farely new and is an Interstate. I'm guessing I will still have to replace it, but for the future I want to make sure my battery doesn't die in the same manner.

Any help or suggestions?? Thanks guys for the help.