Alarm started, won't stop

The Prestige Platinum APS-775 alarm/remote-start system on my 2001 Toyota Camry started alarming spontaneously today and I finally had to unhooked the car's battery to make it stop. An aftermarket dealer installed it within the first month I had the car (bought new, now 24K miles).   I have a valet switch and a remote starter override switch.  I thought toggling the valet switch with the ignition on, then off; or locking/unlocking the doors with the key and pressing the brake would reset the system, but no luck.  It  just kept starting back up.  I cannot start the car, or use any accessories (like windows, door locks, or radio.)

I think it may be related somehow that yesterday I couldn't atomatically lock the doors from the inside with the door button, but the auto-start and auto door locks worked with the remote from the outside.

Today, I set the alarm and left my dog inside, and I heard a 4-beep alarm minutes later that I think he somehow set off.  I turned off the alarm before getting back in and heard nothing more. The car was parked in the driveway for 4-5 hours before it started alarming this afternoon.  I'd never heard it go off before, and it cycled thru it's alarm routine at least 3 times before I realized it was mine.  (I think it should have only gone thru the routine once, but it kept repeating...)

I don't have any reason to think I have a weak car battery.  I had a cellphone adapter plugged in, but I don't think it was using power.   Nothing seemed to have been left on.

Nothing I've tried  would turn the alarm off.  Nothing in the Owner's manual seemed to help.  I'd appreciate any help.