Ok, if you had a M1XRF2G, you'd be in trouble because it is no longer supported by the more recent (5.x.x) firmware releases. Since you have a M1XRFEG, you should be ok.
Did you back up your configuration by doing a Receive All and saving it before you installed the new firmware?
It may be that all you need to do is re-enroll all the bus modules to get the wireless receivers back.