This back cover is held on by tabs. If you lever them around the edges the black back cover will come off.
You can now see the circuit board which is held in with tabs again.
Lift out the circuit board. Be careful not to move any for the controls on the unit or it will be difficult to reassemble.
Remove the needles. I use 2 spoons with some paper to protect the dials
Carefully remove the black frame around the LCD. Gently lift the LCD screen out of the frame and flip it over flat on the table. Rotate the clocks keeping the LCD flat and then carefully remove the white front piece.
You now have the circuit board, be vary careful not to damage the LCD ribbon whilst you are replacing the LED’s. You don’t replace all of the LEDs, look at the photo below to identify which ones to change.