according to Dassault

"...Computer failure or unfitted screws?

Sources said French aeronautics firm Safran made computer controls for the aircraft and it is suspected that the pitch rate gyrometers — the sensors that calculate the aircraft’s altitude — sent a wrong input.

Fighters like the Mirage 2000 are programmed to accept commands from the flight computer to keep the aircraft stable. Flight computers also play a role in release of the missiles or bombs on board in conflict.

“The CoI is now looking at what caused this wrong input. Was it a software problem or was it because three out of the four necessary screws on the sensors were not fitted,” a source in know of the CoI proceedings said.

HAL is carrying out an upgrade of the Mirage 2000 fighters, manufactured by the French firm Dassault.

Sources said the French firm had sought the sensors to be handed over for analysis but HAL refused to do so..."

https://theprint.in/defence/computer-failure-or-hals-botched-upgrade-what-mirage-2000-crash-probe-is-looking-at/247927/