A321 Flight Attendant reported use of emergency lights for deplaning due to a CIDS fail upon gate arrival.

Narrative

CIDS (Cabin Interphone Display System) mechanical issue. Lost control of lights; PA; interphone; while pulling into gate. Seat belt sign turned off; and it appeared we were at the gate. FAP (Forward Attendant's Panel) was displaying an error message; however at this point I had PA control again. Made the disarm PA; but when the seat belt sign turned back on; quickly confirmed with the other FAs that their doors were still armed. Once we got to the gate; and the proper all call was complete; I informed the pilots of what had happened. The Captain confirmed it was a CIDS issue. Everything was working 'normal' at this point; minus the error message on the FAP (Flight Attendant Panel). The pilot left while we were still deplaning. We lost all cabin lights; and I had zero control of the FAP. I had no other choice than to activate the priority lights; so the passengers could continue deplaning. I also contacted Operations; and had them Dispatch Maintenance. Explained what I witnessed to maintenance; and that the priority lights were only on because I had activated them. Following up with an ASAP because of the accidental door disarming PA; due to the seat belt sign being turned off by CIDS.