The battery on my 2008 honda odyssey keeps dying. i puchased a new one and it was dead the following day

SOURCE: How can I get a 2004 Honda Odyssey into neutral

If you have jumper cables, connect them to the honda as if you were going to try to jump it off. Be sure to have your foot on the brake when trying to shift. You can also use a "Settings Saver" that plugs into your cigarette lighter. This will provide enough power to allow it to shift.

SOURCE: 2003 Honda Odyssey Brake light replacement

open the rear hatch. Between the tail light housing and the rear hatch opening there is a trim strip with two flush fitted flap doors. Insert a small straight blade screwdriver into the small slot on the tail light side of the flap. Pry gently inboard and the small flap will open (the hinge side of the flap is on the side of the rear hatch opening.) Now you can remove the screws that hold the tail lamp assembly in place. Finally, there is still a "spear point" clip that fits into a socket near the front outboard corner of the assembly. Gently pry with a tape wrapped screwdriver (avoids scratches) and force the assembly straight back. The clip should release and free the assembly so you can change the bulb(s).

SOURCE: I need radio code for honda odyssey 2004

my code was on the inside of the glove compartment

SOURCE: my 2005 honda odyssey anti theft activated when my

Not trying to steal your solution, but trying to clean up the unanswered page:
There are two possible answers here:
The simple one:  Use your remote control's "unlock" button to reset the anti-theft system.
or a more comlex one that seems to work: (From the original post)"I found out that you remove the horn fuse, shut the doors, put the key in and unlock it two times then put the fuse back in...it resets the anti theft..."

SOURCE: tcs light and engine check light on my 2000 honda odyssey

I had the same code/symptoms a few weeks ago. Dealer did a nice job checking through all the details. Replaced the egr too, but no improvement. Finally found one cylinder not firing correctly (not the same pressure as the other cylinders.) Dealer did a value clean/adjustment, for about $250, and the problem has been gone for about a month now. We are also getting about 15% better mileage.

Hope this helps.