Maintenance Lead Technician reported a Maintenance repair error by clearing an MEL and returning aircraft without accomplishing all required procedures.

Narrative

Aircraft experienced an smoke; odor; or fume event on Day 0. On Day 1 Troubleshooting performed on [Job Card 1] determined APU was possible cause resulting in APU and APU bleed valve both being placed on MEL. On logbook sheet #XXXXXXX Day 2; [Maintenance Control] updates with request to accomplish APU SOF TS (Troubleshooting) card; APU inlet Wash; APU Load comp wash and [Job Card 4] to burn out ECS (Environmental Control System) before releasing APU back into service. On Day 3 under same logbook sheet XXXXXXX; [APU SOF] troubleshooting performed and APU found to be leaking at Scroll and FCU (Fuel Control Unit); but unable to repair so deferral continues with logbook sheet XXXXXXX1 created for reinspect. Logbook sheet XXXXXXX2 created Day 3 to leave APU on MEL until repair can be made and ECS decontamination and load comp wash can be C/W (Complied With). Day 3 logbook sheet XXXXXXX3 created to accomplish APU SOF TS card again after APU found leaking. (On Day 4; after discovery of leaking APU scroll housing and FCU (on Day 3) APU bleed valve was reactivated and APU was placed back in service by Employee with no repair performed.) [Job Card 2] APU SOF TS; Cleaning of APU intake; Wash APU Load Compressor; and ECS decontamination have not been accomplished. No repair to the APU was made to return it to serviceable condition after findings on Day 3. APU was used in service from Day until [overnight maintenance] was completed on Day 5 and the APU was repaired and [inspection] was accomplished. To be clear; the APU MEL was cleared and an unserviceable APU was placed back in service and used [for a period of 7 days].