save firmware image somewhere you can find it again!
log in to ZD
go to tab on top right...
administer
upgrade
screenshot...
you will be asked to backup your ZD configuration (do it).
You might also find the upgrade fails because there is not enough memory (common issue). This requires the event log to be cleared and a ZD reboot. Takes time but straightforward. The same process as above.
I am assuming that the ZD is not controlling any wifi at the moment (because conversation started with R310 not connecting).
Firmware upgrades are routine but need to be carefully considered.
They should only be done after reading release notes and looking for gotchas, incompatibilities and known issues. If you have no functional Wifi then you have nothing to break so in a reasonably "safe" position.
Beat me to it!