Try resetting again as suggested one of the user it works :
You have to restore the firmware backup. After that, the login goes on, but appears an spinning wheel.
Here the steps:
Automatic Firmware Fallback Method:
#1. Turn ON – wait 5 seconds – turn OFF – wait 5 seconds
#2: Turn ON – wait 5 seconds – turn OFF – wait 5 seconds
#3: Turn ON – wait 5 seconds – turn OFF – wait 5 seconds
#4: Turn ON – wait 5 seconds – turn OFF – wait 5 seconds
#5: Turn ON – wait 5 seconds – turn OFF – wait 5 seconds
#6: Turn ON – let the router boot up
still have issue follow below thread :
https://community.cisco.com/t5/small-business-routers/rv340-unable-to-login-to-admin-portal/td-p/4185895