Depending on the model there is a screw (+) or two at the bottom of the control button. Loosening it will allow the control button to come free hinging from the top. Disconnect the wire by pulling or unscrewing the round terminal
Sending your control together with the processor will ensure we test is and verify its operation. The control button failure is not uncommon.
Only the control button within your shower is needed. All other buttons are insignificant (slaves) for the correct operation of your shower