Symptoms

• No sound from rear speaker
• Control center is flashing green (trying to connect)
• Faulty rear speaker led is flashing red immediately after plugging in the power (indicates error)
• OR led totally off

Solutions from internet

Youtube - Logitech Z-5450 Rear Wifi Speaker Cap replacement - 2.0

I have a LogitechSpeaker System Model Z5450 the speakers will...

Repairing the Logitech Z-5450 5.1 THX Surround Sound system

Logitech Z-5450 5.1 surround sound speakers - no sound from rear right only

Trying to fix the rear left wifi speaker

I followed the Youtube video, first link in solutions from internet.

A - Dismounting supposed faulty parts

B - Mounting new parts

After replacing supposed faulty parts

It works again all good.
Fixed red led when no communication with base.
Fixed blue led when base is switched on.
And sound in the speaker.

Edit 24/12/2023: I fixed the rear right speaker the same way.