You are trying with the wrong file.
Before, same code filename was working for USB or TFTP proceedure.
Now, for each proceedure there is another firmware filename. Please see the following:
Initially I was trying with junos-arm-32-15.1X53-D56.tgz but I had the same error 2 as you had.
Then, as per above url, I downloaded junos-install-media-net-arm-32-15.1X53-D56.tgz and worked like a charm.
Steps for the proceedure here: https://kb.juniper.net/InfoCenter/index?page=content&id=KB31462&cat=SWITCH_PRODUCTS&actp=LIST
Have fun!