I was keying in a new arrival after changing runways, I created a PBD waypoint cleared a discontinuity. Right when I did that the MCDU screen flashed and I looked up and the plane was pitching up erratically. I had lost all but essential power (captain pfd was on but not much else) my control inputs did nothing. I looked outside and saw my control surfaces were all locked fully down. I could manipulate the cockpit and displays were responsive so it wasn't a WASM crash. I crashed shortly after. Josh asked for a couple of screenies so I'll attach those
https://imgur.com/a/VVvE2nK
I was passing roughly 15k at that moment on the descend on the IRNMN2 arrival for ILS25L into KLAX. As mention I created a PBD waypoint to make a continuous nav line to the runway. I loaded the plane via the tablet import from simbrief.
see the overview in the imgur link