As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON LEVEL OFF AT FL250 THE CREW RECEIVED THE R2 SERVICE DOOR UNSAFE LIGHT. CREW RAN QRH CHECKLIST, DETERMINED PRESSURIZATION WAS HOLDING, DID A RAPID DESCENT TO FL100 AND DEPRESSURIZED IN ACCORDANCE WITH QRH AND DIVERTED TO PIT. FOUND DOOR HANDLE POPPED OUT, DOOR OPS CHECKED GOOD.