The LED is an important aspect to indicate the intensity of the wireless connectivity. When disabled, it will be automatically enabled upon joining to another remote wireless network.

While it maybe slightly unpleasant in view, the best suggestion currently would be to apply a small piece of black electrical insulating tape over the LED. When needed, it can be easily unpeeled to reveal the signal.

The LED disabling in the EZwizard menu will be considered for Future firmware release

With Firmware version 5.71, you can disable/enable  the LED from the EZwizard menu.

However, version 5.71 can only be manually flashed at the moment.

http://ezwifi.eu/what-why-how/firmware/v5-ez511/5-71/rel-2019-12-20-scheduled

A Newer Version 5.73 is however also scheduled to be released in May/June from the OTA Firmware Upgrade menu. 

During a Hard Factory Reset, any blinking LED in any fashion is normal and the initiation may take up to 9 minutes to complete, after which the LED will be blinking in less active manner. The blinking interval contrast will be easily recognized in person.

A Solid Green LED upon start up that lasts more than 30 seconds and followed by no blinking activity may indicate a corrupted file system. It can be recovered with our recovery package. Kindly see below link.

http://ezwifi.eu/what-why-how/firmware/led-remains-solid-green-after-firmware-upgrade

When ezhotspot extender is powered up, it takes normally 30~45 seconds before the private SSID is broadcasted and ready for use.

• Single quick LED  - device's operating system is booting.
  
  
• Alternate Blue & Green slow LED - device is ready and private SSID is broadcasted.