General Maintenance & Repairs - 01 WS6 wont start please help

I recently talked my little brother into buying a 01 ws6. It was stock but now has Lts and true duals. The car had 167,000 miles. yesterday we did a oil change on it and were also trying to figure out why the head lights dont go up or down. after we were done working on it we started it up, and turned it off to check fluid levels. About 1 hour later he went to leave and the car wouldnt start. The factory alarm started going off (we dont have the factory remote for the car). We tried to get in put the key in and hit the unlock but that didnt work. I noticed the unlock button is currently not working. The security light on the dash is flashing. I even tried to take the battery off for about 10 min but that didnt work either. Any suggestions? Thanks in advance

It's more than likely your VATS system that has gone bad. Common problem now that these cars are so old. Do a search on it there are a few fixes.

The wire that passes resistance from the key chip through the steering column broke. Found the resistance of the key and pick up some resistors from radio shack and crimped them in line....... Car started right up

Glad you found the issue...VATS strikes again

I just had to get my vats system done on my car it was about 340.00