I hate to say it, but look for water intrusion under the floor mat (where your feet rest) both sides of the cabin.
Open the box with the PTCM/RCB/BCM and look for water in there.
Look also in the passenger rear fender in the trunk for water intrusion.

Several items you bring up suggest the car thinks it's moving when it's not.
But the flashing lights suggest a security module/skreem issue.

I'm left wondering if something is screwing up the CAN bus, like water intrusion on a module somewhere.

This one sounds like one for Rudy....