The version 1.5 cannot be updated. When the BMPlus was upgraded to accommodate heatpump thermostats and multistage heatpump equipment, the hardware architecture and processor were changed. To get set up properly you will need to replace the existing control panel.
If you wish to use just single stage heat/cool thermostats and allow the panel to control the staging, we recommend the BMPlus5000 Rev. B (Version 2.9). If you wish to allow the thermostats to control the staging using multistage heatpump thermostats we recommend the Model UZC6.
The List price of the EWT-3611 (I wrote the incorrect number in my earlier post) is $99