As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER SITTING ON THE GROUND FOR 10 MINUTES WITH BOTH ENGINE RUNNING THE COMPASS CARD ON BOTH NAVIGATION DISPLAYS SWING FROM OUR CURRENT HEADING OF 160 TO 060 AND BACK TWICE AND "SPEED BRAKE" WAS AURALLY ANNUNCIATED. GROUNDED - YES. NO FAULTS FOUND ON ADIRU, FMC, & OMF BITE REF AMM 34-21-00 & 34-61-00. FOR ADDITIONAL INFO REF 737MAX-FTD-34-17003 ISSUE 4 IN REGUARDS TO SPEEDBRAKE WARNIGN OCCURING ON GROUND.