Battery flat alarm going off when trying to jump from fuse box plug

[Jhinson]

It seems every year I go through this and you would think I would learn. I had the hook left cracked open and covered up this year but someone most have helped me out and pushed it down. However, as normal I have a battery portable battery jumper that I have used the past 3 years, pulling the red jump slider all the way out putting the positive on it and the black clip on the door hinge to get a good ground and it has worked perfectly for 3 years. Today I attempted this and the horn starts honking and no power to anything inside as normal, the front hood will not respond nor will anything else just the horn honking. I then tried a lawn mower 12 volt battery fully charged with the same result. As it was honking I put the key in the door and turned it tried to the right then to the left with no result, tried putting key in ignition and turning it to the right with no effect no lights nothing but the loud horn honking. I was thinking that maybe if I were inside with the door closed if this may work but cant find a good enough ground with the door closed and of course the windows are closed. The car is a 2001 boxster S if that matters. I was certain that I did not set the alarm when in storage but it has been 6 months so I could have done anything. Maybe get a cigarette lighter charger? Normally this thing only needs just a small amount of juice before I can at least pop the hood. Help....I have gotten online and can't find any post where this is the exact scenario. Regards. JH