Wow..

The 5 x 5 beep is the backup alarm for the airbag system. This is in the owner's manual.

Replace the airbag warning lite in the cluster and the beeping will go away. Now, with a primary warning indicator that works, you can count the flashes to get a two-digit lamp Fault Code (LFC) that will guide you towards diagnosing the fault in the airbag system.

Steve