According to this answer, turning on Apollo 13's Service Module Propulsion System was considered risky since ground control ditn't know if it was damages in the explosion
Perform a PC+2 hour abort burn with the Service Module Propulsion System for a landing at 118+00 in the Pacific Ocean. This option was rejected unanimously as being too risky since no data was available as to the structural integrity of the Service Module. This option was put into the category of "last ditch".
Did NASA ever find out if the engine was damaged that bad that it would have exploded had it been turned on?