I replaced the battery now the alarm light is on and my car wont start

It is in theft mode

try this - Try disconnecting the battery for one hour. Make sure the ignition key is not in the ignition. Then reconnect the battery. Place the ignition key in ignition and switch to accessory position. Reset your dash clock to the correct time. Making sure everything is switched off. Air con, fans, radio, lights, and wipers and any other accessories this also includes anything plugged into the cigarette lighter such as a mobile or cell phone. Make sure all doors are closed. Also if there is a HOLD button near your gear change make sure it is in the upper position (switched off). Then in PARK press the accelerator pedal down twice. Remove foot off pedal and start vehicle. Allow several days running for the vehicle to computer self tune and memorize running conditions

The green light is flashing still won't start

and my radio and clock would not work? And my green light keep flashing.