The firmware update process is reliable, but the modules can rarely get bricked. You should be able to unbrick your module by following the instructions below.
First, connect the bricked module to your UHK.
Right-click on the "Flash firmware" button and a context menu should appear containing the possibly bricked modules:
(The context menu will not appear if both of your modules are connected and recognized by Agent. The touchpad module will not appear in the menu because its firmware is not upgradeable.)
Select the relevant module in the list, and Agent should unbrick the module.
You may have to repeat the unbricking process several times for it to succeed.