Two possible mistakes I can see - you say you are going to Hot water sensor, but you are then trying to bind the BRD91 ? That won't work, the BDR91 is an actuator not a sensor. When you set up hot water you bind both the sensor (CS92) and the hot water relay, (BDR91) in different steps, so if you are putting the relay into binding mode when it is expecting the sensor to be in binding mode then naturally it will not show anything.
The other possible issue is you say you hold the button down for 15 seconds (which clears all previous bindings) and then continue to hold it another 5 seconds to bind - I believe you're supposed to release the button after you get the rapid flash after 15 seconds then press and hold it again for 5 seconds to go into binding mode. Only actuators have a clear binding operation, sensors don't need to be cleared before rebinding.
Also I think you're supposed to put the evotouch into binding mode first and then the sensor or actuator that you're binding. I've found if I do it the other way around it can take a long time (minutes) for the binding to register, I presume because the sensor/actuator sent its binding request before the evotouch was ready, and then doesn't re-transmit a request for quite a while.
You don't need to use guided mode to rebind hot water - I would recommend going to System Devices->Stored Hot water and change hot water configuration to disabled, and follow the prompts to remove the hot water configuration.
Then hold the button on the hot water BDR91 for 15 seconds until you get the rapid flash to show that its binding had been cleared. (It will continue with a rapid flash until you re-bind it later)
Then to re-add hot water go back into System Devices->Stored Hot water and choose enable.
It will then ask you to bind the sensor - so put the CS92 into binding mode. After that has bound the next step should ask you to bind the hot water zone valve - now put the BDR91 into binding mode by holding the button for 5 seconds - the flashing will change from fast to slow and then stop after a few seconds when the Evotouch completes the binding.
Hope that helps - I don't have a hot water kit so can't test all the steps myself but the above should be correct.
PS when you do the binding are you taking the Evotouch off its stand and taking it to within a metre or so of the BDR91 and CS92 ?