If customer by mistake uploaded incorrect X.509 Certificate on ICON unit, Web UI of ICON unit won't be accessible.
Remove incorrect X.509 certificate from ICON unit using below steps:
1) SSH to ICON unit using Putty: ssh admin@icon_IP (Ex. ssh firstname.lastname@example.org)
2) Put Password: (Default password is admin. Else put password of user "admin" configured by customer.)
3) Put command: SysAdmin remove509Cert
4) Put command: SysAdmin reboot 1
5) Unit will reboot and customer will be able to access web UI of ICON unit using ICON IP address.
Below is screen-shot of command for reference: