As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: EMERGENCY LIGHT TEST FAILED DURING PS CHECK. FAULT EPSU(10WL) FWDL/DEU-B(300RH1) ATA 335138. AFTER TROUBLE SHOOTING FOUND WIRE FROM EPSU (10WL) TO R1 DOOR SLIDE OPEN. MAINTENANCE REPLACED R1 DOOR ESCAPE SLIDE IAW J/C 26L00025011.