Anti-theft alarm activated and truck will not start
 

Help! I replaced the water pump on my 2001 Dakota SLT With 3.9 liter motor. Battery was disconnected at beginning and reconnected 24 hours or so later. Vehicle was moved in and out of garage by putting key in ignition and transmissions into neutral. After completing the repairs reattached battery and now horn blares (no flashing lights) and car will not start. Tried key thing to no avail. There is a red LED pin jack under the driver's dash that appears to be used car dealer installed that keeps blinking.

Any and all advice will be greatly appreciated.

find the brain and yank it, should be tucked up in the dash

Try disconnecting your remote device it will automatically switch off the alarm and you can start the truck then

It sounds similar to what my truck has, if yours has power locks you can disarm it by unlocking the doors with the passenger power lock switch.