Basically what you seing is the phone-home client for zero touch provisioning. To disable this, you have to login via serial console, go into configuration mode and delete the 'system phone-home' part of the configuration.
I expect your swith is with the factory default meaning something like the following commands (login with root and no password):
%cli
{master:0}
root> configure
Entering configuration mode
{master:0}[edit]
root# delete system phone-home
{master:0}[edit]
root# commit and-quit
then you should be able to access the basic j-web package on your EX3400. Regarding software access, create a case for customer care mentioning the serial number for your device... you will then be given access to download of software for your EX switch.